Laterally adjustable armrest assembly

ABSTRACT

An adjustable armrest assembly for a bariatric chair is provided. The adjustable armrest assembly for a chair, the armrest assembly comprises: a stationary linkage which is connectable to the chair; an armrest member for supporting an arm of an individual when seated in the chair; a coupling member coupling the armrest member to the stationary linkage, the coupling member permitting travel of the armrest member relative to the stationary linkage; and, a locking element configured for acting on the coupling member to effect locking of the armrest member in any one of at least three indexed positions relative to the stationary linkage.

FIELD OF THE INVENTION

The present invention relates generally to laterally adjustable armrest assemblies. In particular, the present invention relates to laterally adjustable armrest assemblies for bariatric chairs.

BACKGROUND OF THE INVENTION

One of the most critical seating dimensions associated with bariatric chairs is the seat width. Since bariatric patients typically accumulate the majority of their weight around their lower torso and upper thighs, the seat width determines if the bulk of the bariatric patient will properly fit the chair. Similarly, when a bariatric chair design incorporates armrests, the limiting dimension that determines the width-wise fit of the chair to the bariatric patient becomes the distance between the insides of the armrests, which is usually equivalent to or close to the true width of the seating surface. When dealing with shower and commode chairs, which are generally communal among the residents of a bariatric healthcare facility, a seat width that may be functional for one bariatric patient may be too big or too small for another. The typical solution would be to accommodate the largest bariatric patient and sacrifice a comfortable armrest position for smaller patients, or conversely, to accommodate the smaller patients and remove the armrest for any especially large bariatric patients. Although accommodating bariatric patients in chairs that do not adequately fit them may be economically practical for a facility, the chair becomes uncomfortable for individual users as well, potential safety issues are created. By not having the full and proper use of the armrests to steady themselves, the bariatric occupant of the chair will feel laterally unsupported and instable, which creates a psychological discomfort and anxiety. However, in the case where an occupant begins to fall over the edge of the seat, without armrests, there are no restraints or supports for the patient to steady them self with to prevent the fall.

Another challenge associated with accommodating especially wide seats on bariatric shower and commode chairs is caregiver usability in areas where maneuvering space is limited. That is the ability for the caregiver to push the width of the chair through doorways and other narrow openings, as well as manipulating the chair in and around tight spaces commonly found in showering areas and washrooms in healthcare facilities. The actual source of the physical interference caused by extra wide seats can usually be attributed to the external width across the armrests. Since armrests are typically mounted on the outside of the seat width, to ensure proper arm positioning, this mounting position places them at the widest section of the chair and makes them the most likely source of interference. For this reason many shower and commode chairs for bariatric patients have either removable armrests or armrests that are mounted within the width of the seating surface, which effectively reduces the seat width.

The width between the armrests also has an effect as to how easy shower and commode chairs are to use as well as how comfortable they are to sit in. For example, when bathing a bariatric patient it is common to have the excess flesh from around the thighs fill the seat width up to the front and rear armrest support members. When this happens it becomes difficult for the caregiver to wash these areas hidden by the armrest hardware because of the limited access to the occupant. Also, by not having adequate clearance between the chair hardware and the occupant, bariatric patients cannot be transferred to and from the chair as easily. Since most bariatric patients are heavier than what is typically allowed for manual transfers, caregivers rely a great deal on being able to use motorized or hydraulic transfer lifts that utilize full body slings to support the body.

These lifting slings need to be wrapped around strategic areas of the body in order to function properly and safely. In non-bariatric cases the occupant of the chair could easily reposition themselves or be repositioned by the caregiver to expose any inaccessible areas that need washing or to allow transfer lift body slings to be fitted. However when dealing with bariatrics patients, repositioning the person is not easily achieved due to their extreme size and weight. In most cases the bariatric shower chair would have provisions for swing-away, swing-up, flip-down, or removable armrests which would allow the caregiver to access any areas that were being blocked by the armrests. The cost of this solution is that the armrests become unusable for that duration, making the chair uncomfortable and potentially unsafe for the bariatric patient to sit in since they would be required to support the entire weight of their own arm as well as loose any form of lateral support to stabilize themselves.

When a bariatric chair is used for commode activities it is a common desire and necessity for most people, and especially men, to relax and widen their legs in order to comfortably void themselves. If the commode chair is correctly sized when the bariatric patient is seated normally, opening their legs becomes impossible because the front vertical supports of the armrests will interfere with theirs knees and will prevent the occupant from moving their thighs outward. Due to the nature of most commode chair seats, with the commode pan reservoir positioned to match the regular seated position, the person cannot reposition themselves sufficiently forward to spread their legs without creating a misalignment with the commode reservoir. If the commode chair has provisions for swing-away, swing-up, flip-down, or removable armrests the occupant's legs can be accommodated, but again at the expense of loosing the use, security, and comfort of the armrests.

SUMMARY OF THE INVENTION

According to one broad aspect of the present invention, there is provided an adjustable armrest assembly for a chair, the armrest assembly comprising: a stationary linkage which is connectable to the chair; an armrest member for supporting an arm of an individual when seated in the chair; a coupling member effecting coupling of the armrest member to the stationary linkage, the coupling member permitting travel of the armrest member relative to the stationary linkage; and, a locking element configured for acting on the coupling member to effect locking of the armrest member in any one of at least three indexed positions relative to the stationary linkage.

In one aspect, permitted travel of the armrest member relative to the stationary linkage is along an arc-like path.

In another aspect, the coupling member is a swivel linkage.

In yet another aspect, the swivel linkage comprises a stationary linkage coupling portion and an armrest coupling portion, the stationary linkage coupling portion being offset from the armrest coupling portion, the stationary linkage coupling portion further being rotatably coupled to the stationary linkage, thereby permitting rotatable movement of the swivel linkage relative to the stationary linkage, and the armrest coupling portion being rotatably coupled to the armrest member, thereby permitting rotatable movement of the swivel linkage relative to the armrest member.

In a further aspect, the armrest member includes an armrest coupling linkage for effecting the rotatable coupling to the swivel linkage, and wherein the locking element includes a detent pin which is biased to interfere with the relative rotational movement between the swivel linkage and the armrest coupling linkage, such that the locking in an indexed position is effected by the detent pin being positioned in both a swivel linkage hole provided in the swivel linkage and in a respective armrest coupling hole provided in the armrest coupling linkage, the detent pin becoming so positioned when the swivel linkage hole and the respective armrest coupling linkage hole are disposed in an overlapping relationship, the swivel linkage hole and the respective armrest coupling linkage hole becoming so disposed upon relative rotational movement between the swivel linkage and the armrest coupling linkage.

In yet a further aspect, the locking element is coupled to one of the swivel linkage and the armrest coupling linkage.

In a further aspect, a threaded handwheel is provided and configured for acting on the coupling member and effecting locking of the armrest member in positions other than the at least three indexed positions.

According to a further broad aspect, there is provided an armrest assembly for a chair, the armrest assembly comprising a stationary linkage configured for coupling to the chair; an armrest member including an upper surface configured for supporting at least a portion of a forearm of a person when seated in the chair, wherein the upper surface includes an uppermost surface portion; at least two swivel linkages effecting coupling of the armrest member to the stationary linkage, each of the at least two swivel linkages including a respective stationary linkage coupling portion rotatably coupled to the stationary linkage for rotation about a respective swivel linkage-stationary linkage axis, and also including a respective armrest member coupling portion rotatably coupled to the armrest member for rotation about a respective swivel linkage-armrest member axis; wherein each of the at least two swivel linkages is characterized by a respective offset distance, wherein the respective offset distance is the distance between the respective swivel linkage-stationary linkage axis and the respective swivel linkage-armrest member axis in a plane which is tangent to the uppermost surface portion; wherein the at least two swivel linkages includes a most forwardly disposed swivel linkage, such that the swivel linkage-stationary linkage axis of the most forwardly disposed linkage is forwardly disposed relative to the respective swivel linkage-stationary linkage axis of each of the other of the at least two swivel linkages and the swivel linkage-armrest member axis of the most forwardly disposed linkage is forwardly disposed relative to the respective swivel linkage-armrest member axis of each of the other of the at least two swivel linkages; wherein the at least two swivel linkages also includes a most rearwardly disposed swivel linkage, such that the swivel linkage-stationary linkage axis of the most rearwardly disposed swivel linkage is rearwardly disposed relative to the respective swivel linkage-stationary linkage axis of each of the other of the at least two swivel linkages and the swivel linkage-armrest member axis of the most rearwardly disposed swivel linkage is rearwardly disposed relative to the respective swivel linkage-armrest member axis of each of the other of the at least two swivel linkages; and wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.2 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.

In a further aspect, there is provided an armrest assembly for a chair, the armrest assembly comprising a stationary linkage configured for coupling to the chair; an armrest member including an upper surface configured for supporting at least a portion of a forearm of a person seated in the chair, wherein the upper surface includes an uppermost armrest surface portion; at least two swivel linkages effecting coupling of the armrest member to the stationary linkage, each of the at least two swivel linkages including a respective stationary linkage coupling portion rotatably coupled to the stationary linkage for rotation about a respective swivel linkage-stationary linkage axis, and also including a respective armrest member coupling portion rotatably coupled to the armrest member for rotation about a respective swivel linkage-armrest member axis; wherein each of the at least two swivel linkages is characterized by a respective offset distance, wherein the respective offset distance is the distance between the respective swivel linkage-stationary linkage axis and the respective swivel linkage-armrest member axis in a plane which is tangent to the uppermost surface portion; wherein the at least two swivel linkages includes a most forwardly disposed swivel linkage and a most rearwardly disposed swivel linkage; and wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.2 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.

In yet a further aspect, there is provided a chair comprising a chair frame; and an armrest assembly including: a stationary linkage coupled to the chair frame; an armrest member including an upper surface configured for supporting at least a portion of a forearm of a person seated in the chair, wherein the upper surface includes an uppermost surface portion; at least two swivel linkages effecting coupling of the armrest member to the stationary linkage, each of the at least two swivel linkages including a respective stationary linkage coupling portion rotatably coupled to the stationary linkage for rotation about a respective swivel linkage-stationary linkage axis, and also including a respective armrest member coupling portion rotatably coupled to the armrest member for rotation about a respective swivel linkage-armrest member axis; wherein each of the at least two swivel linkages is characterized by a respective offset distance, wherein the respective offset distance is the distance between the respective swivel linkage-stationary linkage axis and the respective swivel linkage-armrest member axis in a plane which is tangent to the uppermost surface portion; wherein the at least two swivel linkages includes a most forwardly disposed swivel linkage, such that the swivel linkage-stationary linkage axis of the most forwardly disposed linkage is forwardly disposed relative to the respective swivel linkage-stationary linkage axis of each of the other of the at least two swivel linkages and the swivel linkage-armrest member axis of the most forwardly disposed linkage is forwardly disposed relative to the respective swivel linkage-armrest member axis of each of the other of the at least two swivel linkages; wherein the at least two swivel linkages also includes a most rearwardly disposed swivel linkage, such that the swivel linkage-stationary linkage axis of the most rearwardly disposed swivel linkage is rearwardly disposed relative to the respective swivel linkage-stationary linkage axis of each of the other of the at least two swivel linkages and the swivel linkage-armrest member axis of the most rearwardly disposed swivel linkage is rearwardly disposed relative to the respective swivel linkage-armrest member axis of each of the other of the at least two swivel linkages; and wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.2 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.

In another aspect, there is provided a chair comprising a chair frame; and an armrest assembly including a stationary linkage coupled to the chair frame; an armrest member including an upper surface configured for supporting at least a portion of a forearm of a person seated in the chair, wherein the upper surface includes an uppermost surface portion; at least two swivel linkages effecting coupling of the armrest member to the stationary linkage, each of the at least two swivel linkages including a respective stationary linkage coupling portion rotatably coupled to the stationary linkage for rotation about a respective swivel linkage-stationary linkage axis, and also including a respective armrest member coupling portion rotatably coupled to the armrest member for rotation about a respective swivel linkage-armrest member axis; wherein each of the at least two swivel linkages is characterized by a respective offset distance, wherein the respective offset distance is the distance between the respective swivel linkage-stationary linkage axis and the respective swivel linkage-armrest member axis in a plane which is tangent to the uppermost surface portion; wherein the at least two swivel linkages includes a most forwardly disposed swivel linkage and a most rearwardly disposed swivel linkage; and wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.2 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.

In one aspect, the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.5 times longer than the respective offset distance of the most rearwardly disposed linkage.

In another aspect, the most forwardly disposed swivel linkage has a respective horizontal offset distance which is at least 2 times longer than the respective horizontal offset distance of the most rearwardly disposed linkage.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention are described below with reference to the accompanying drawings in which:

FIG. 1 is a front perspective view of a bariatric chair having an armrest assembly according to an embodiment of the present invention;

FIG. 2 is a side elevation view of a bariatric chair having an armrest assembly according to an embodiment of the present invention;

FIG. 3 is a front elevation view of bariatric chair having an armrest assembly according to an embodiment of the present invention;

FIG. 4 is a rear elevation view of bariatric chair having an armrest assembly according to an embodiment of the present invention;

FIG. 5 is a top plan view of bariatric chair having an armrest assembly according to an embodiment of the present invention;

FIG. 6 is a perspective view of an armrest assembly of the chair according to an embodiment of the present invention;

FIG. 7 is an exploded perspective view of an armrest assembly of the chair according to an embodiment of the present invention;

FIG. 8 is a plan view of an armrest assembly of the chair in a first narrow position according to an embodiment of the present invention;

FIG. 9 is a plan view of an armrest assembly of the chair in a wide position according to an embodiment of the present invention;

FIG. 10 is a plan view of an armrest assembly of the chair in a second narrow position according to an embodiment of the present invention;

FIG. 11 is a cross-sectional side elevation view of an armrest assembly of the chair according to an embodiment of the present invention, illustrating a hand wheel lock in an engaged position; and

FIG. 12 is a cross-sectional side view of the armrest of FIG. 11, illustrating the hand wheel locked in a disengaged position.

FIG. 13 is a top perspective view of a backrest of a chair according to an embodiment of the present invention;

FIG. 14 is a side elevation view of a backrest of a chair according to an embodiment of the present invention;

FIG. 15 is an exploded view of a seat of a chair according to an embodiment of the present invention;

FIG. 16 is a front perspective view of a chair frame of a chair according to an embodiment of the present invention;

FIG. 17 is an illustration of an extendible/retractable support member of a chair according to an embodiment of the present invention;

FIGS. 18 and 19 are, respectively, the side elevation view and a front elevation view of the combined seat and backrest of a chair according to an embodiment of the present invention, illustrating the relationship between various components of the seat and backrest;

FIGS. 20A, 20B, 20C, and 20D are, respectively, a side elevation view, a top plan view, a further side elevation view, and yet a further side elevation view, of the combined seat and backrest of a chair according to an embodiment of the present invention, further illustrating the spatial relationship between the components of the chair and the backrest;

FIGS. 21, 22, 23 and 24 are, respectively, a side elevation view, a top plan view, a further side elevation view, and a front elevation view of the combined seat and backrest of a chair according to an embodiment of the present invention, illustrating various points of reference to define dimensions of the backrest;

FIGS. 25 and 26 are, respectively, a side elevation view and a top plan view of a combined seat and backrest of a chair according to an embodiment of the present invention, illustrating the relationship between various components of the seat and backrest to assist in defining the cross-sectional area of a recess provided by the chair;

FIGS. 27, 28 and 29 are, respectively, a side elevation view, a top plan view, and a further side elevation view of a combined seat and backrest of a chair according to an embodiment of the present invention, illustrating the relationship between various components of the seat and back rest to assist in defining the depth of a recess provided by the chair;

FIGS. 36, 31 and 32 are, respectively, a side elevation view, a top plan view, and a further side elevation view of a combined seat and backrest of a chair according to an embodiment of the present invention, illustrating the relationship between various components of the seat and the backrest in order to assist in defining a depth of a recess provided by the chair;

FIGS. 33 and 34 are, respectively, a side elevation view and a top plan view of a combined seat and backrest of a chair according to an embodiment of the present invention, illustrating the relationship between various components of the seat and the backrest in order to assist in defining the height of a recess provided by the chair;

FIGS. 35, 36 and 37 are, respectively, a front elevation view, a top plan view, and a side elevation view of a combined seat and backrest of a chair according to an embodiment of the present invention, illustrating the relationship between various components of the seat and the backrest in order to assist in defining the spatial relationship between such components;

FIGS. 38 and 39 are side elevation views of a combined seat and backrest of a chair according to an embodiment of the present invention, illustrating the relationship between various components of the seat and the backrest in order to assist in defining a depth of a recess provided along a width segment of the chair;

FIG. 40 is a side elevation view of a combined seat and backrest of a chair according to an embodiment of the present invention, illustrating the relationship between various components of the seat and the backrest in order to assist in defining a height of a recess provided along a width segment of the chair;

FIG. 41 is a side elevation view of a combined seat and backrest of a chair according to an embodiment of the present invention, illustrating the relationship between various components of the seat and the backrest in order to assist in defining a cross-sectional area of a recess extending along a width segment of the chair; and

FIG. 42 is a bottom plan view of a seating element of a chair according to an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Referring to FIGS. 6 and 7, an adjustable armrest assembly 500 for the bariatric chair 10 is illustrated according to an embodiment of the present invention. The armrest assembly 500 comprises an armrest 522 for supporting a forearm of an individual when seated in the chair 10, and a coupling member 555 for coupling the armrest 522 to an armrest side (550 a or 550 b) of the chair 10. The armrest 522 includes an upper surface 5222 configured for supporting at least a portion of a forearm of a person occupying the chair 10. The upper surface 5222 includes an uppermost surface portion 5224. The coupling member 555 facilitates lateral movement of the armrest 522 relative to the chair 10 between at least three indexed armrest positions. The armrest assembly 500 also includes a locking mechanism 900 configured for acting on the coupling member 555 so as to effect locking of the armrest 522 in any one of the at least three indexed locked positions.

It is understood that, when the armrest 522 becomes locked in one of the at least three indexed locked positions, the armrest 522 may or may not be completely stationary, and if not completely stationary, then the armrest 522 may move (ie. travel) a minor distance owing to the fact that interacting components which effect locking of the armrest 522 in the one of the at least three indexed locking positions are configured with some play between them.

It is also understood that the at least three indexed armrest positions are distinguished from one another by the fact that the spatial disposition of the armrest 522 when locked in any one of the at least three indexed positions is never identical to the spatial disposition of the armrest 522 when locked in any of the other of the at least three indexed positions. However, it is also understood that the spatial disposition of a first portion of the armrest, when the armrest 522 is disposed in a first spatial position, may overlap (ie. occupy the same space) with the spatial disposition of a second portion of the armrest 522, when the armrest 522 is disposed in a second spatial position. For example, referring to FIGS. 8 and 10 which illustrate the armrest 522 in respective forward narrow and rearward narrow positions, portion ‘A’ of the armrest 522 is shown moving laterally and rearwardly as the armrest 522 moves from the forward narrow position (FIG. 8) to the wide rearward narrow position (FIG. 10). When the armrest 522 is in the forward narrow position, portion ‘B’ of the armrest 522 is disposed in (occupies) a certain space, relative to the chair 10. When the armrest 522 is in the rearward narrow position, portion ‘A’ of the armrest 522 is disposed in this same space (ie. the space occupied by portion ‘B’ when the armrest 522 is disposed in the forward narrow position). In this respect, the spatial disposition of portion ‘A’, when the armrest 522 is lateral in a first position, overlaps with the spatial disposition of portion ‘B’ when the armrest 522 is lateral in a second position.

With particular reference to the case where the armrest 522 is not completely stationary when locked in at least one of the at least three indexed positions, it is also understood that the at least three indexed armrest positions are distinguished from one another by the fact that, where there is some movement of the armrest 522 when in one of the at least one of the at least three indexed positions, the various spatial dispositions of the armrest 522 within the scope of travel of the armrest 522 in such indexed position are never identical to the spatial disposition or dispositions (in the case where there is minor movement of the armrest 522 in another indexed position) of the armrest in any of the other of the at least three indexed positions (although a spatial disposition of a portion of the armrest 522, when the armrest 522 is disposed in a first spatial position, may overlap with a spatial disposition of a second portion of the armrest 522, when the armrest 522 is disposed in a second spatial position).

In the embodiment illustrated in FIG. 1, the chair 10 is configured with an armrest assembly 500 on each armrest side 550 a, 550 b of the chair 10. FIGS. 6 and 7 illustrate an armrest assembly 500 of one side 500 a of the chair 10. The armrest assembly 500 for the opposite side 550 b of the chair 10 is a mirror image of the armrest assembly of the side 550 a of the chair 10.

The armrest assembly 550 can form an integral part of the chair 10. Alternately, the armrest assembly 550 may be configured for connection to the chair. In the embodiment illustrated in FIG. 1, two armrest assemblies 500 are provided, and each is connected to a respective one of the opposite armrest sides 550 a, 550 b of the chair 10.

The armrest 522 may include any padded armrest known to those skilled in the art. For example, the armrest 522 may include a molded plastic material. As a further example, the armrest 522 is constructed of self-skinning polyurethane foam molded over a plywood inner cores and has two internally embedded threaded steel inserts used for fastening. It will be apparent to those skilled in the art that any armrest that can support an arm of an individual when seated in the chair may be employed.

In the illustrated embodiment, the coupling member 555, which permits lateral movement of the armrest member 522 relative to the chair 510, is a four-bar linkage assembly as is known to those skilled in the art. The four-bar linkage assembly comprises a stationary linkage 565, swivel linkages 570, 670, and an armrest coupling linkage 575.

The stationary linkage 565 is either configured for coupling to an armrest side 500 a (or 500 b) of the chair 10, or is formed as an integral part of the chair 10 and is disposed at an armrest side 500 a (or 500 b) of the chair 10. In the illustrated embodiment, the stationary linkage 565 is integral to the chair 10, and the stationary linkage 575 forms a portion of each of the upper rails 84 a, 84 b (as each side 500 a, 500 b includes an armrest assembly 500).

The swivel linkages 570 and 670 are provided to effect coupling of the armrest coupling linkage 575 to the stationary linkage 565 while facilitating lateral movement of the armrest coupling linkage 575 relative to the stationary linkage 565. Each of the swivel linkages 570, 670 is rotatably connected to the stationary linkage 565 in spaced-apart relationship to one another along a length of the stationary linkage 565 such that the swivel linkage 570 is rotatably connected to the stationary linkage 565 closer to the front of the chair 10 and the swivel linkage 670 is rotatably connected to the stationary linkage 565 closer to the back of the chair 10.

Each of the swivel linkages 570, 670 is also rotatably connected to the armrest coupling linkage 575 in spaced apart relationship to one another along a length of the armrest coupling linkage 575, such that the swivel linkage 570 is rotatably connected to the armrest coupling linkage 575 closer to the front of the chair and the swivel linkage 670 is rotatably connected to the armrest coupling linkage 575 closer to the back of the chair 10. The connection of each of the swivel linkages 570, 670 to the armrest coupling linkage 575 is offset relative to the respective connection of each of the swivel linkages 570, 670 to the stationary linkage 565.

The armrest coupling linkage 575 is connected to the armrest member 522, such as by screw 521.

The stationary linkage 565 includes an elongated frame member 510 having a front joint portion 577 and a back joint portion 579, such that the front joint portion 577 is positioned closer to the front of the chair 10 and the back joint portion 579 is positioned closer to the back of the chair 10. Each of the joint portions 577, 579 preferably includes a respective one of offset posts 511 a, 511 b. Each of the posts 511 a, 511 b extends laterally from the frame member 510 and includes a respective one of sockets 512 a, 512 b. Each of the sockets 512 a, 512 b is in the form of a tube segment defining a throughbore 5124 having a substantially circular cross-section along its length between respective ends of the tube segment. An axis passing through the throughbore 5124 of each of the respective socket 512 a, 512 b is oriented orthogonally to the longitudinal axis of the respective offset post 511 a, 511 b (FIG. 7).

The swivel linkage 570 includes a stationary linkage joint portion 525 and an armrest joint portion 516. The stationary linkage joint portion 525 is offset from the armrest joint portion 516 and joined to the armrest joint portion 516 by a laterally extending connector 517. The stationary linkage portion 525 is rotatably connected to the socket 512 a of the stationary linkage 565, thereby facilitating rotatable movement of the swivel linkage 570 about the axis passing through the socket 512 a.

The stationary joint portion 525 includes upper and lower concentric cylindrical segments 5252, 5254. The diameter of the upper segment 5252 is greater than the diameter of the lower segment 5254. The segment 5254 is received within and rotatably engaged to the socket 512 a. The lower segment 5254 is joined to the upper segment 5252 by a surface 5256 extending peripherally and outwardly from the lower segment 5254. The surface 5256 is seated upon a shoulder portion 5122 of the socket 512 (and thereby effecting vertical support of the surface 5256 by the shoulder portion 5122) when the tube segment 5252 is received within the socket 512 a. In this respect, the stationary joint portion 525 is rotatably connected to the socket 512 a and is configured for rotation relative to the socket 512 a about the axis 5251. In the illustrated embodiment, the axis is 5251 vertical.

A locking mechanism 701 is provided to prevent disengagement of the stationary joint portion 525 from the socket 512 a by limiting upwards displacement of the stationary joint portion 525 relative to the socket 512 a. When the locking mechanism 701 is in the operative condition, the stationary joint portion 525 is secured to the socket 512 a. When the locking mechanism 701 is in an inoperative condition, the stationary joint portion 525 is unsecured relative to the socket 512 a. The stationary joint portion 525 is secured to the socket 512 a by effecting interference of upwards displacement of the stationary joint portion 525 relative to the socket 512 a. Such interference action is accommodated by having the stationary joint portion 525 extend through and below the socket 512 a, and having a lower portion 5258 of the lower segment 5254 of the stationary joint portion 525 extending below the socket 512 a coupled to a moveable detent 703 which selectively abuts against a lower end of the socket 512 a if an attempt is made to pull the stationary joint portion 525 out of the socket 512 a.

In order for the stationary joint portion 525 to assume an unsecured condition relative to the socket 512 a, the detent 703 is configured so as to be capable of receding to a position which does not interfere with the upwards displacement of the stationary joint portion 525 relative to the socket 512 a. When the detent 703 is so receded, the locking mechanism 701 is in the inoperative condition. When the detent 703 is in the outwardly extended position, interfering with the upwards displacement as described above, the locking mechanism 701 is in the operative condition.

To facilitate the above-described operation of the locking mechanism 701, the socket 512 a is open ended at both ends 530 a, 531 a and the throughbore 5124 joins the ends 530 a, 531 a. This permits insertion of the stationary joint portion 525 into the socket 512 a such that the lower portion 5258 extends below the socket 512 a. Also, stationary joint portion 525 includes a bore 5260 which communicates externally of the stationary joint portion 525 through a hole 5262 provided in the sidewall of the lower portion 5258. The bore 5260 and the hole 5262 accommodate the locking mechanism 701.

The locking mechanism 701 includes a detent pin spring 705 having first and second portions 707, 709, and the detent pin 703 coupled to the spring 705 between the first and second portions 707, 709. The detent spring 705 is disposed within the bore 5260. When the locking mechanism 701 is in the operative condition, the first and second portions 707, 709 bear against a respective one of opposing inner surface portions of the stationary joint portion 525, and the detent pin 703 is positioned within and extends through the hole 5262 and outwardly relative to the lower portion 5258 (thereby providing a means for interfering with upwards displacement of the stationary joint end 525 relative to the socket 512 a, as discussed above) by the biasing force exerted by the spring 705. When the locking mechanism 701 is in the inoperative condition, the detent pin 703 is positioned in alignment with the hole 5262 but disposed so as not to extend outwardly relative to the external surface of the lower portion 5258. In this position, the detent pin 703 does not interfere with upwards displacement of the stationary joint portion 525 relative to the socket, and thereby permits the stationary joint end 525 to be pulled out of the socket 512. The detent pin 703 can be moved to this position from its extended position outside of the hole 5262 by applying a manual force on the pin 703 in a direction opposite to, and overcoming the biasing force imparted by the spring 705.

The armrest joint portion 516 is rotatably connected to the armrest coupling linkage 575 closer to the front of the chair 10 relative to the connection of an armrest joint portion 616 of the swivel linkage 670 to the armrest coupling linkage 575 (see below). The armrest joint portion 516 preferably includes upper and lower concentric cylindrical segments 5162, 5164. The diameter of the lower segment 5164 is greater than the diameter of the upper segment 5162. The segment 5162 is received within a bore 5753 of a cylindrical tubular segment 5752 of the armrest coupling linkage 575, and thereby is rotatably engaged to the segment 5752. The upper segment 5162 is joined to the lower segment 5164 by a surface 5166 extending peripherally and outwardly from the upper segment 5162. The surface 5164 functions as a shoulder or seating surface upon which the segment 5752 of the linkage 575 is seated when the segment 5162 is disposed within the segment 5752, thereby effecting vertical support of the segment 5752 by the surface 5164. The armrest joint portion 516 is configured for rotation relative to the segment 5752 about an axis 5161. In the illustrated embodiment, the axis 5161 is vertical.

The swivel linkage 570 is, therefore, rotatably coupled to the stationary linkage 656 for rotation about the axis 5251, and is also rotatably coupled to the armrest coupling linkage 575 for rotation about the axis 5161. The distance between the axis 5251 and the axis 5161 (see FIG. 11), in the plane 5220 which is tangent to the uppermost surface portion 5224, is denoted by reference numeral 2.

The swivel linkage 670 includes a stationary linkage joint portion 625 and an armrest joint portion 616. The stationary linkage joint portion 625 is offset from the armrest joint portion 616 and joined to the armrest joint portion 616 by a laterally extending connector 617. The stationary linkage joint portion 625 is rotatably connected to the socket 512 b of the stationary linkage 665, thereby facilitating rotatable movement of the swivel linkage 670 about the axis passing through the socket 512 b.

The stationary joint portion 625 includes upper and lower concentric cylindrical segments 6252, 6254. The diameter of the upper segment 6252 is greater than the diameter of the lower segment 6254. The segment 6254 is received within and rotatably engaged to the socket 512 b. The lower segment 6254 is joined to the upper segment 6252 by a surface 6256 extending peripherally and outwardly from the lower segment 6254. The surface 6256 is seated upon a shoulder portion 6122 of the socket 512 (and thereby effecting vertical support of the surface 6256 by the shoulder portion 6122) when the tube segment 6254 is received within the socket 512 b. In this respect, the stationary joint portion 625 is rotatably connected to the socket 512 b and is configured for rotation relative to the socket 512 b an axis 6251. In the illustrated embodiment, the axis 6251 is vertical.

A locking mechanism 801 is provided to prevent disengagement of the stationary joint portion 625 from the socket 512 b by limiting upwards displacement of the stationary joint portion 625 relative to the socket 512 b. When the locking mechanism 801 is in the operative condition, the stationary joint portion 625 is secured to the socket 512 b. When the locking mechanism 801 is in an inoperative condition, the stationary joint portion 625 is unsecured relative to the socket 512 b. The stationary joint portion 625 is secured to the socket 512 b by effecting interference of upwards displacement of the stationary joint portion 625 relative to the socket 512 b. Such interference is accommodated by having the stationary joint portion 625 extend through and below the socket 512 b, and having a lower portion 6258 of the lower segment 6254 of the stationary joint portion 625 extending below the socket 512 b coupled to a moveable detent 803 which is configured to abut against a lower end of the socket 512 b if an attempt is made to pull the stationary joint portion 625 out of the socket 512 b.

In order for the stationary joint portion 625 to assume an unsecured condition relative to the socket 512 b, the detent 803 is configured so as to be capable of receding to a position which does not interfere with the upwards displacement of the stationary joint portion 625 relative to the socket 512 b. When the detent 803 is so receded, the locking mechanism 801 is in the inoperative condition. When the detent 803 is in the outwardly extended position, interfering with the upwards displacement as described above, the locking mechanism 801 is in the operative condition.

To facilitate the above-described operation of the locking mechanism 801, the socket 512 b is open ended at both ends 630 a, 631 a and the throughbore 6124 joins the ends 630 a, 631 a. This permits insertion of the stationary joint portion 625 into the socket 512 b such that the lower portion 6258 extends below the socket 512 b. Also, stationary joint portion 6525 includes a bore 6260 which communicates externally of the stationary joint portion 625 through a hole 6262 provided in the sidewall of the lower portion 6258. The bore 6260 and the hole 6262 accommodate the locking mechanism 801.

The locking mechanism 801 includes a detent pin spring 805 having first and second portions 807, 809, and the detent pin 803 coupled to the spring 805 between the first and second portions 807, 809. The detent spring 805 is disposed within the bore 6260. When the locking mechanism is in the operative condition, the first and second portions 807, 809 bear against a respective one of opposing inner surface portions of the stationary joint portion 625, and the detent pin 803 is positioned within and extends through the hole 6262 and outwardly relative to the lower portion 6258 (thereby providing a means for interfering with upwards displacement of the stationary joint end 525 relative to the socket 512 a, as discussed above) by the biasing force exerted by the spring 805. When the locking mechanism 801 is in the inoperative condition, the detent pin 803 is positioned in alignment with the hole 6262 but disposed so as not to extend outwardly relative to the external surface of the lower portion 6258. In this position, the detent pin 803 does not interfere with upwards displacement of the stationary joint portion 625 relative to the socket, and thereby permits the stationary joint end 625 to be pulled out of the socket 512. The detent pin 803 can be moved to this position from its extended position outside of the hole 6262 by applying a manual force on the pin 803 in a direction opposite to, and overcoming the biasing force imparted by the spring 805.

The armrest joint portion 616 is rotatably connected to the armrest coupling linkage 575 closer to the back of the chair 10 relative to the connection of an armrest joint portion 516 of the swivel linkage 570 to the armrest coupling linkage 575. The armrest joint portion 616 preferably includes upper and lower concentric cylindrical segments 6162, 6164. The diameter of the lower segment 6164 is greater than the diameter of the upper segment 6162. The segment 6162 is received within a bore 6753 of a cylindrical, tubular segment 6752 of the armrest coupling linkage 575, and thereby is rotatably engaged to the segment 6752. The upper segment 6162 is joined to the lower segment 6164 by a surface 6166 extending peripherally and outwardly from the upper segment 6162. The surface 6164 functions as a shoulder or seating surface upon which the segment 6752 of the linkage 575 is seated when the segment 6162 is disposed within the segment 6752, thereby effecting vertical support of the segment 6752 by the surface 6166. The armrest joint portion 616 is configured for rotation relative to the segment 6752 about an axis 6161. In the illustrated embodiment, the axis 6161 is vertical.

The swivel linkage 670 is, therefore, rotatably coupled to the stationary linkage 565 for rotation about the axis 6251, and is also rotatably coupled to the armrest coupling linkage about the axis 6161. The distance between the axis 6251 and the axis 6161 (see FIG. 12), in the plane 5220 (which is tangent to the uppermost surface portion 5224), is denoted by reference numeral 4

In one embodiment, the distance 2 is the same or substantially the same as the distance 4. In another embodiment, the distance 2 is at least 1.2 times longer than the distance 4 (ie. the ratio of the distance 2 to the distance 4 is 1.2). For example, the distance 2 is at least 1.5 times longer than the distance 4. As a further, further example, the distance is at least two (2) times longer than the distance 4. By having the distance 2 being longer than the distance 4, additional space is provided between the armrest assemblies 500 a, 500 b closer to the front of the chair than closer to the rear of the chair 10. Typically, a bariatric patient seated in the chair 10 requires additional room for comfort closer to the front of the chair, and this is accommodated by having the distance 2 being longer than the distance 4.

The armrest coupling linkage 575 includes a front joint portion 589 from which the segment 5752 extends downwardly, and a back joint portion 591, from which the segment 6752 extends downwardly. The armrest linkage 575 is rotatably connected to each of (i) the armrest joint portion 516 of linkage 570, and (ii) the armrest joint portion 616 of the linkage 670, by a respective one of the segments 5752, 6752, thereby permitting rotatable movement of the swivel linkages 570, 670 about the respective axes 5161, 6161 and lateral movement of the armrest coupling linkage 575 relative to the stationary linkage 565 (and also, therefore, relative to the chair 10).

The front and back joint portions 589, 591 are joined by an elongated frame member 520. The armrest member 522 is suitably connected to the elongated member 520 so as to present a surface upon which a person seated in the chair can rest his or her arms on the armrest member 522 for support. In the illustrated embodiment, the armrest member 522 is connected to the frame member 520 by screws 521 a, 521 b.

A locking mechanism 900 is provided to selectively limit relative rotational movement between the swivel linkage 570 and the armrest coupling linkage 575 and between the swivel linkage 670 and the armrest coupling linkage 575, when the armrest is in any one of a first narrow armrest position, an intermediate wide armrest position, or a second narrow armrest position. An example of the above-described relative rotational movement being limited by the locking mechanism 900 is when the above-described relative rotational movement is substantially prevented by the locking mechanism 900. In this context, the term “substantially prevented” means that the above-described relative rotational movement may or may not be prevented, and if not prevented, the above-described relative rotational movement is limited such that the relative rotational movement between the linkages 570, 670 and the linkage 575 is minor and not sufficiently significant so as to noticeably derogate from the chair occupant's expectations that his or her arm is maintained in a stationary position when supported on the armrest 522.

The locking mechanism 900 includes at least a first locking element 902. The first locking element 902 is configured to act between the swivel linkage 570 and the armrest coupling linkage 575 to oppose tangential forces relative to swivel linkages 560, 670, being applied by the armrest coupling linkage 575 that would otherwise effect swivelling of the linkages 560, 570. This limits (for example, substantially prevents) the above-described rotational movement of the linkages 560, 670 relative to the linkage 575 and thereby maintain the armrest 522 in any one of the three above-described positions. In the illustrated embodiment, the locking mechanism 900 includes a second locking element 952. The second locking element 952 is configured to act between the swivel linkage 670 and the armrest coupling linkage 575 to oppose tangential forces relative to swivel linkages 560, 670, being applied by armrest coupling linkage 575 that would otherwise effect swivelling of the linkages 560, 670. This assists locking element 902 by distributing loading between two locking elements instead of only one locking element in limiting (for example, substantially preventing) the above-described relative rotational movements.

The locking mechanism 900 is in the operative condition when relative rotational movement between the swivel linkage 570 and the armrest coupling linkage 575, and between the swivel linkage 670 and the armrest coupling linkage 575, is limited (for example, substantially prevented). The locking mechanism 900 is in the operative condition when at least one of the locking elements 902, 952 is acting between the armrest coupling linkage 575 and a respective one of the swivel linkages 570, 670. When both of the locking elements 902, 952 are acting in this manner, each locking element 902, 952 is individually described as being in an operative condition.

The locking mechanism 900 is in the inoperative condition when each of the swivel linkages 570, 670 is free to rotate relative to the armrest coupling linkage 575, subject to any interference to the rotational movement provided by other components of the assembly 500 or the chair 10 (such as stationary linkage 565). The locking mechanism 900 is in the inoperative condition when the locking element 902 is not acting between the armrest coupling linkage 575 and the swivel linkage 570 (in which case, locking element 902 can also be described as being in an “inoperative condition”), and the locking element 952 is not acting between the armrest coupling linkage 575 and the swivel linkage 670 (in which case, locking element 952 can also be described as being in an “inoperative condition”). In other words, for the locking mechanism 900 to be in the inoperative condition, each of the locking elements 902, 952 must also be in the inoperative condition.

The locking element 902 acts between the swivel linkage 570 and the armrest coupling linkage 575 by effecting interference of relative rotational movement between the swivel linkage 570 and the armrest coupling linkage 575 (as well as linkages 670 and 575). The locking element 902 is coupled to the swivel linkage 570 and includes a moveable detent pin 904. The detent pin 904 is configured to be received within and extend through an armrest linkage hole 528 provided in the sidewall of the segment 5752 of the armrest coupling linkage 575. In other words, the detent pin 904 is configured to interfere with the relative rotational movement between the swivel linkage 570 and the armrest coupling linkage 575. In this respect, when the detent pin 904 extends through the armrest linkage hole 528, and an attempt is made to effect relative rotation between the swivel linkage 560 and the armrest coupling linkage 575, the detent pin 904 becomes abutted against an inner edge surface of the armrest coupling linkage 575 which defines the hole 528, thereby limiting relative rotational movement between the swivel linkage 570 and the armrest coupling linkage 575.

In order for the swivel linkage 570 to assume an unsecured condition relative to the armrest coupling linkage 575, the detent pin 904 is configured to be capable of receding to a position which does not interfere with the relative rotational movement between the swivel linkage 570 and the armrest coupling linkage 575. When the detent pin 904 is so receded, the locking element 902 in the inoperative condition. When the detent pin 904 is in an outwardly extended position, extending through the hole 528, and thereby interfering with the above-described relative rotational movement, the locking element 902 is in the operative condition.

To accommodate the locking element 902, the armrest joint portion 516 of the swivel linkage 570 includes a bore 5601 which communicates externally of the armrest joint portion 516 through a swivel linkage hole 523 provided in the sidewall of the upper segment 5162.

The locking element 902 includes a detent spring 906 having first and second portions 908, 910. The detent pin 904 is coupled to the spring 906 between the first and second portions 908, 910. The detent spring 906 is disposed within the bore 5601 and the first and second portions 908, 910 bear against a respective one of opposing inner surface portions of the armrest joint portion 516.

When the locking element 902 is in the operative condition, both of the armrest linkage hole 528 and the swivel linkage hole 523 are aligned, the first and second portions 908, 910 bear against a respective one of opposing inner surface portions of the armrest joint portion 516, and the detent pin 904 is positioned within and extends through each of the swivel linkage hole 523 and the armrest linkage hole 528 by the biasing force exerted by the spring 906.

When the locking element 902 is in the inoperative condition, the detent pin 904 extends through the swivel linkage hole 523 but does not extend into the armrest linkage hole 528 and, therefore, does not interfere with relative rotational movement between the swivel linkage 560 and the armrest coupling linkage 575. The detent pin 904 can be moved to this receded position from its extended position through the hole 528 by applying a manual force on the pin 904 in a direction opposite to, and overcoming the biasing force imparted by the spring 906.

Once the pin 904 is moved into and maintained in this receded position, the swivel linkage 560 and the armrest coupling linkage 575 can be meaningfully rotated relative to one another, thereby taking the holes 523 and 528 out of alignment. As a result, the detent pin 904 is biased into a position wherein the detent pin 904 extends through the swivel linkage hole 526 and is in sliding contact with the inner surface of the bore 5753 of the segment 5752. However, such contact does not interfere with relative rotational movement between the swivel linkage 560 and the armrest coupling linkage 575 so long as the friction created by spring 906, between detent pin 904 and the inner surface of the bore 5753 is significantly less than the rotational force acting at that interface. For example, this would be the case where the bore 5753 has a circular or substantially circular cross-section along its length which receives the segment 5162.

The segment 5752 includes a plurality of holes 528 about its perimeter, wherein each of the plurality of holes corresponds to a desired indexed position of the armrest 522. In the illustrated embodiment, the segment 5752 includes three (3) holes 528, wherein each of the holes 528 corresponds to a respective one of a first narrow armrest position, an intermediate wide armrest position, and a second narrow armrest position. The armrest 522 is disposed in one of these positions whenever the detent pin 904 extends through a respective one of the holes 528. The armrest 522 moves between these positions as the armrest coupling linkage 575 rotates relative to the swivel linkage 560 from a position of alignment of one of the holes 528 with the hole 523 of the swivel linkage 560 (ie. a first operative condition of the locking element 902) to a position of alignment of another one of the holes 528 with the hole 523 (ie. a second operative condition of the locking element 902).

The locking element 952 acts between the swivel linkage 670 and the armrest coupling linkage 575 by effecting interference of relative rotational movement between the swivel linkage 670 and the armrest coupling linkage 575. The locking element 952 is coupled to the swivel linkage 670 and includes a moveable detent pin 954. The detent pin 954 is configured to be received within and extend through an armrest linkage hole 628 provided in the sidewall of the segment 6752 of the armrest coupling linkage 575. In other words, the detent pin 954 is configured to interfere with the relative rotational movement between the swivel linkage 670 and the armrest coupling linkage 575. In this respect, when the detent pin 954 extends through the armrest linkage hole 628, and an attempt is made to effect relative rotation between the swivel linkage 570 and the armrest coupling linkage 575, the detent pin 954 becomes abutted against an inner edge surface of the armrest coupling linkage 575 which defines the hole 628, thereby limiting relative rotational movement between the swivel linkage 670 and the armrest coupling linkage 575.

In order for the swivel linkage 670 to assume an unsecured condition relative to the armrest coupling linkage 575, the detent pin 954 is configured to be capable of receding to a position which does not interfere with the relative rotational movement between the swivel linkage 670 and the armrest coupling linkage 575. When the detent pin 954 is so receded, the locking element 952 is in the inoperative condition. When the detent pin 954 is in an outwardly extended position, extending through the hole 628, and thereby interfering with the above-described relative rotational movement, the locking element 952 is in the operative condition.

To accommodate the locking element 952, the armrest joint portion 616 of the swivel linkage 670 includes a bore 6601 which communicates externally of the armrest joint portion 616 through a swivel linkage hole 623 provided in the upper segment 6162.

The locking element 952 includes a detent spring 956 having first and second portions 958, 960. A detent pin 956 is coupled to the spring 956 between the first and second portions 958, 960. The detent spring 956 is disposed within the bore 6601 and the first and second portions 908, 910 bear against a respective one of opposing inner surface portions of the armrest joint portion 616.

When the locking element 660 is in the operative condition, both of the armrest linkage hole 628 and the swivel linkage hole 623 are aligned, the first and second portions 958, 960 bear against a respective one of opposing inner surface portions of the armrest joint portion 516, and the detent pin 954 is positioned within and extends through each of the swivel linkage hole 623 and the armrest linkage hole 628 by the biasing force exerted by the spring 956.

When the locking element 954 is in the inoperative condition, the detent pin 954 extends through the swivel linkage hole 623 but does not extend into the armrest linkage hole 628 and, therefore, does not interfere with relative rotational movement between the swivel linkage 670 and the armrest coupling linkage 575. The detent pin 954 can be moved to this receded position from its extended position through the hole 628 by applying a manual force on the pin 954 in a direction opposite to, and overcoming the biasing force imparted by the spring 956.

Once the pin 954 is moved into and maintained in this receded position, the swivel linkage 670 and the armrest coupling linkage 575 can be rotated relative to one another, thereby taking the holes 623 and 628 out of alignment. As a result, the detent pin 954 is biased into a position wherein the detent pin 954 extends through the swivel linkage hole 628 and is in sliding contact with the inner surface of the bore 6753 of the segment 6752. However, such contact does not interfere with relative rotational movement between the swivel linkage 670 and the armrest coupling linkage 575 so long as the friction created by the spring 906 between detent pin 904 and the inner surface of the bore 6753 is significantly less than the rotational force acting at that interface. For example, this would be the case where the bore 6753 has a circular or substantially circular cross-section along its length which receives segment 6162.

The segment 6752 includes a plurality of holes 628 about its perimeter, wherein each of the plurality of holes corresponds to a desired indexed position of the armrest 522. In the illustrated embodiment, the segment 6752 includes three (3) holes 628, wherein each of the holes 628 corresponds to a respective one of a forward narrow armrest position, an intermediate wide armrest position, and a rear narrow armrest position. The armrest 522 is disposed in one of these positions whenever the detent pin 954 extends through a respective one of the holes 628. The armrest 522 moves between these positions as the armrest coupling linkage 575 rotates relative to the swivel linkage 670 from a position of alignment of one of the holes 628 with the hole 623 of the swivel linkage 670 (ie. a first operative condition of the locking element 952) to a position of alignment of another one of the holes 628 with the hole 623 (ie. a second operative condition of the locking element 952).

The armrest assembly 500 is moveable between at least three indexed positions. In the embodiment illustrated in FIGS. 1, 8, 9 and 10, the armrest assembly 500 is moveable between three indexed positions, namely: a forward narrow position (FIG. 8), in which the armrest 522 is in a narrow position at about the front end of the chair 10, a mid-wide position (FIG. 9), in which the armrest 522 is in a wide position at about the mid-point of the chair 10, and a rear narrow position (FIG. 10), in which the armrest 522 is in a narrow position at about the back of the chair 10. As the assembly 500 moves to each of these positions, the armrest 522 follows an arc-like path, which is generally indicated by the arrow in each of FIGS. 8, 9 and 10. This arc-like path, results in lateral movement of the armrest 522 relative to the chair 10, between a forward narrow position, an intermediate wide position, and a rearward narrow position. For example, the lateral distance moved between either of the narrow positions and the wide position is no greater than three (3) inches. As a further example, this lateral distance moved is two (2) inches.

In an alternate embodiment, the coupling member 555 comprises a single swivel linkage of a configuration identical to that of either swivel linkage 570 or 670, and would be rotatably connected to the stationary linkage 565 in an identical manner to that described for the coupling of either of the swivel linkages 570, 670 to a respective one of the sockets 12 a, 12 b of the stationary linkage 565. The single swivel linkage would be further rotatably connected to the armrest coupling linkage 575 in an identical manner to that described for the coupling of either of the swivel linkages 570, 670 to the respective one of the segments 5752, 6752 of the armrest coupling linkage 575. For example, the single swivel linkage would be connected to the armrest coupling linkage 575 at about a midpoint of the armrest coupling linkage 575 (as opposed to one of the end portions 589, 591) so as to realize a more stable structure. The locking mechanism 900 associated with the single swivel linkage would be a single locking element 902 or 954, and would be configured to limit (for example, substantially prevent) relative rotational movement between the single swivel linkage and the armrest coupling linkage 575. Also, a single locking mechanism of the configuration described and illustrated for either locking mechanism 701 or 801 could also be provided for preventing disengagement of the stationary joint portion of the single swivel linkage from an associated socket of the linkage 575.

In another embodiment the armrest assembly 500 includes more than two swivel linkages to effect coupling of the linkage 575 to the linkage 565.

Movement of the illustrated embodiment of the armrest 522 between the forward narrow position, the wide position, and the rearward narrow position will now be described. Initially, the armrest 522 is in the forward narrow position (see FIG. 8), and each of the locking elements 902, 952 is in the operative condition. As a first step, each of the detent pins 904, 954 is manually depressed so that they recede into each of their corresponding respective holes 528, 628, such that the detent pins 904, 954 are in a position wherein they cannot interfere with a respective one of relative rotational movement between linkage 570 and linkage 515 and relative rotational movement between linkage 670 and linkage 575 (ie. the locking elements 902, 952 are in the inoperative condition). A manual force is then applied to the intermediate armrest 522 to effect movement of the armrest 522 in an arc-like path from the forward narrow position to the wide position (see FIG. 9). As the armrest 522 moves in this manner, each of the linkages 570, 670 rotates relative to the linkages 575, and each of the detent pins 904, 954 moves out of alignment with a respective one of a first set of holes 528, 628. When the armrest 522 assumes the intermediate wide position, each of the detent pins 904, 954 is biased to extend through a respective one of the second set of holes 528, 568 so that each of the locking elements 902, 952 assumes a second operative position, thereby locking the armrest 522 in the intermediate wide position. To move the armrest 522 from the intermediate wide position to the rearward position (see FIG. 10), the detent pins 904, 954 are, again, manually depressed so that they recede into each of their corresponding respective holes 528, 628, such that the detent pins 904, 954 are in a position whereby they cannot interfere with a respective one of relative rotational movement between linkage 570 and linkage 575 and relative rotational movement between linkage 670 and linkage 575 (ie. the locking elements 902, 952 are in the inoperative condition) A manual force is then applied to the armrest to effect movement of the armrest in an arc-like path from the intermediate wide position to the rearward position (See FIG. 10). As the armrest 522 moves in this manner, each of the linkages 570, 670 rotates relative to the linkage 575, and each of the detent pins 904, 954 moves out of alignment with a respective one of the second set of holes 528, 628. When the armrest 522 assumes the rearward narrow position, each of the detent pins 904, 954 assumes alignment with a respective one of a third set of holes 528, 628, and the detent pins are biased to extend through a respective one of the third set of holes 528, 628, so that each of the locking elements 902, 952 assumes a third operative position, thereby locking the armrest 522 in the rearward position.

Referring to FIGS. 6, 7, 11 and 12, the locking mechanism 900 may further include a threaded handwheel to act between at least one of: (i) the linkage 560 and the linkage 575, and (ii) the linkage 670 and the linkage 575, and thereby provide a further means for effecting interference of relative rotational movement between both sets of linkages (linkages 560, 575 and linkages 570, 575). In the illustrated embodiment, two threaded handwheels 1001, 1101 are provided. The handwheel 1001 acts between the linkage 560 and the linkage 575. The handwheel 1101 acts between the linkage 670 and the linkage 575.

The handwheel 1001 includes a threaded rod 1003 that threadably engages a projection nut 1005 coupled to the segment 5752 of the linkage 575. The nut 1005 defines a bore 1007 which is co-axial with an opening provided in the segment 5752 of the armrest coupling linkage 575. The opening is a circular hole that has a diameter which is large enough to accept the major diameter of the threaded rod 1003. The handwheel 1001 can be turned so as to extend through the opening and bear against the upper segment 5162 of the armrest joint portion 516 of the swivel linkage 560, thereby interfering with relative rotational movement between the linkages 560 and 575 (as well as linkages 570 and 575). The second handwheel 1101 is configured to bear against linkage 570 in a similar manner. The handwheel 1101 includes a threaded rod 1103 that threadably engages a projection nut 1105 coupled to the segment 6752 of the linkage 575. The nut 1105 defines a bore 1107 which is co-axial with an opening provided in the segment 6752. The opening is a circular hold that has a diameter which is large enough to accept the major diameter of the threaded rod 1003. The handwheel can be turned so as to extend through the opening and bear against the upper segment 6162 of the armrest joint portion 616 of the swivel linkage 670, thereby interfering with relative rotational movement between the linkages 670 and 575 (as well as linkages 560 and 575).

Each of the handwheels 1001, 1101 is capable of limiting relative movement between both sets of linkages when the armrest 522 is not disposed in one of the three indexed positions (ie. the armrest 522 is disposed in a non-indexed position), which is the case when holes 523 and 528 are out of alignment (or when holes 623 and 628 are out of alignment).

Accordingly, when the detent pins 904, 954 and the handwheel 1001 are in their respective disengaged positions, the armrest linkage 575 may be moved to a desired lateral position (FIG. 12). If this position does not correspond to an indexed position, then the handwheel 1003 may be engaged to thereby lock the sets of linkages and prevent further lateral movement of the armrest linkage 575 (FIG. 11).

In one embodiment, the adjustable armrest assembly is coupled to the chair 10. Referring to FIG. 1, the chair 10 is provided including a chair frame 12, a seat 14, and a backrest 16. The chair frame 12 supports the seat 14 and the backrest 16 upon a reaction surface 8.

Referring to FIG. 16, the chair frame 12 includes a structural frame supported on rolling means. The structural frame comprises two unitary side structures 900 a, 900 b joined by cross braces 961, 962. The elements of the structural frame are made of one inch diameter, 16 gauge (ie. 0.065 of an inch wall thickness) stainless steel tubing. The structural frame is supported on each side by front casters 100 a, 100 b and rear casters 110 a, 110 b, and a wheel 101 a, 101 b intermediate the front and rear casters. For example, the casters 100 a, 10 b, 110 a, 110 b are Tente™ brand five inch diameter stainless steel locking casters. For example, the wheels 101 a, 101 b are Colson™ brand eight inch diameter Performa™ wheels with stainless steel axles.

The chair frame 12 includes two unitary side structures 900 a, 900 b. Each of the side structures 900 a, 900 b includes a respective one of upper rails 90 a, 90 b, a respective one of front vertical members 91 a, 91 b, and a respective one of lower rails 93 a, 93 b. Each of the upper rails 90 a, 90 b and each of the lower rails 93 a, 93 b extend rearwardly from a respective one of the front vertical member 91 a, 91 b and are joined to a respective one of rear vertical members 911 a, 911 b at the rear of the chair frame 12.

The unitary structures 900 a, 900 b are joined together by cross braces 961, 962. Spaced apart lowered cross member braces 98 a, 98 b extend rearwardly and downwardly from cross brace 961.

Each brace 98 a, 98 b is pivotally coupled to one end of a respective one of a pair of extendible/retractable members 200 a, 200 b (see FIGS. 1, 2, and 4) by a respective bolt extending through a respective pair of aligned apertures, one of the respective pair of aligned apertures being provided in a respective one of the braces 98 a, 98 b and the other being provided in a respective one of the members 200 a, 200 b. Each of the extendible/retractable members 200 a, 200 b is pivotally coupled at a second opposite end to the seat 14 (see below) by a respective bolt extending through a respective pair of aligned aperture, one of the respective pair of aligned apertures being provided in a respective one of a pair of posts 81 a, 81 b provided on the seat frame 18 (see below) and the other of the respective pair of aligned apertures being provided in a respective one of the members 200 a, 200 b. The members 200 a, 200 b support the seat 14 in various positions of tilt.

A lowered cross brace 97 is also provided, extending between and joining the unitary structures 900 a, 900 b, and coupled to each of the braces 98 a, 98 b. The brace 97 provides additional support to the braces 98 a, 98 b which are loaded by the weight of the chair occupant being translated to the extendible/retractable members 200 a, 200 b.

Each of the front casters 100 a, 100 b is coupled to and depends from the lower end of a respective one of the front vertical members 91 a, 91 b. Each of the rear casters 110 a, 110 b is coupled to and depends from a respective one of the rear vertical members 911 a, 911 b. Each of fixed wheels 101 a, 101 b is provided intermediate respective casters 100 a, 100 b and casters 110 a, 110 b. Each of the wheels 101 a, 101 b is coupled to a respective one of the upper rails 90 a, 90 b by a respective one of first and second forks 94 a, 94 b and 95 a, 95 b.

The seat 14 is coupled to the chair frame 12. The seat 14 includes a seat frame 18 and a seating element 19 having a seating surface 20. The seating surface 20 is configured for generally receiving and supporting a portion of the bottom torso of a person occupying the chair (the “chair occupant”). The seating surface 20 can be a continuous or a discontinuous surface. The seating surface 20 can include discontinuous portions so long as the seating surface 20 performs the function of providing the necessary support to the chair occupant. An example of a suitable discontinuous surface is a plurality of spaced apart vinyl straps that are coupled to the seat frame. The plurality of vinyl straps function, in concert, to provide the necessary support to the chair occupant, and the existence of spaces between the vinyl straps does not necessarily render the vinyl straps incapable of performing the above-described function.

In the illustrated embodiment, the seating element 19 is configured to permit the chair occupant to expel bodily wastes into a receiving container 73 disposed below the seat (as further described below). In this respect, the seating element 19 includes a centrally positioned opening 22 defined by the seating surface 20 extending from and merging with a front edge 24 of the seating surface 20. The front edge 24 extends laterally from either side of the opening 22 and merges with side edges 26, 28 of the seating surface 20. The side edges 26, 28 extend from the front edge 24 to a rear edge 30 of the seating surface 20. The rear edge 30 is disposed opposite to the front edge 24 and joins the side edges 26, 28. It is understood that any of the front edge 24, rear edge 30, or side edges 26, 28 can be continuous or discontinuous. In this respect, these edges can include discontinuous portions so long as such edge or edges define the perimeter of a seating surface which functions to provide the necessary support to the chair occupant.

A width of the seating surface 20 is defined as any distance of the seating surface 20 (including any discontinuous portions of the surface 20) between the side edges 26, 28 and along any vertical plane parallel to a vertical plane that is tangent to the most forwardly disposed surface of the front edge 24. A length of the seating surface 20 is defined as any distance of the seating surface 20 (including any discontinuous portions of the surface 20) between the front edge 24 and the rear edge 30 and along any vertical plane having a transverse axis that is perpendicular to the normal axis of a vertical plane tangent to the most forwardly disposed outermost surface of the front edge 24.

The seating surface 20 includes a seating surface portion having a minimum width and a minimum length. In this respect, the width and/or the length may not be consistently the same for the entire seating surface portion but, rather, may vary between a minimum and a maximum. For example, the minimum width is 27 inches and the minimum length is 22 inches. As a further example, the minimum width is at least 18 inches, and the minimum length is at least 20 inches. In yet a further example, the minimum width is between 18 inches and 38 inches, and the minimum length is between 16 inches and 24 inches.

For example, the seating element 19 is constructed with black polyurethane foam molded over a medium density fiberboard structural inner core. It is coupled to the seat frame via four polyurethane foam locating bosses 2002 a, 2002 b 2003 a, 2003 b and a front locating flange 2001 (see FIG. 42) that are molded on the underside of the seating element 19 and are configured for alignment with the structural elements of the seat frame 18 to prevent the seat from sliding relative to the seat frame 18. The seat remains positioned on the seat regardless of shifts in weight because the foam locating bosses mate with the structural elements of the seat frame and, because of the friction created by the weight of the occupant bearing down on the foam seat and the seat frame. As long as the planar force created by the shift in weight of the occupant does not exceed the combined shear threshold of the locating bosses and the interface friction between the foam seat and the seat frame, then the seat remains substantially stationary.

Referring to FIG. 15, the seat frame 18 is made of one inch square, 16 gauge (ie. 0.065 of an inch wall thickness) stainless steel tube and includes a pair of unitary side structures 800 a, 800 b, each coupled to a respective one of the sides of a main support structure 700. The main support structure 700 includes a tube structure 77 for supporting the seating surface 20 and the receiving container 73. The tube structure 77 is shaped to facilitate unobstructed communication between an opening 22 (defined by the seating surface 20) and the receiving container 73 vertically aligned with the opening 22. The main support structure 700 includes a pair of spaced apart posts 82 a, 82 b for pivotal coupling of a legrest 300 thereto by a pair of bolts, each of the bolts extending through a respective pair of aligned apertures, one of the respective pair of aligned apertures being provided in a respective one of posts 82 a, 82 b and the other of the respective pair of aligned apertures being provided in a respective one of an opposing pair of portions of the legrest 300. The main support structure 700 also includes u-shaped members 78, 79 provided for effecting support of the receiving container 73. The u-shaped members 78, 79 are coupled to and depend below the tube structure 77 in spaced apart relation to each other. Tube end caps 88 are provided to close the apertures of the tube structures.

In the illustrated embodiment, the receiving container 73 is in the form of a bed pan having a peripherally extending lip 731 with notches 732 for engaging a resilient container support structure 72. The container support structure 72 is, for example, a 3/16 of an inch diameter stainless steel rod formed and welded to the desired shape. The container support structure 72 is provided to support and secure the receiving container 73 to the u-shaped members 78, 79 of the seat frame 12. The container support structure 72 is shaped to support the receiving container 73 about the lip 731, and includes mounting rods 75 a, 75 b and 76 a, 76 b for being received within corresponding apertures provided in the u-shaped members 78, 79. To further stabilize the receiving container 73 versus the container support structure 72, notches 732 are provided on either side of the container 73 for receiving the mounting rods 76 a, 76 b. To effect mounting of the container support structure 72 to the chair frame 12, the container support structure 72 is manually bent so that the mounting rods become aligned with the corresponding apertures, and then the mounting rods are inserted into the corresponding apertures. The receiving container 73 can then be mounted upon the container support structure 72.

Each of the side structures 800 a, 800 b is coupled to the main support structure 700 by a cross brace 80. Each of the side structures 800 a, 800 b includes a respective one of the upper seat rails 84 a, 84 b and a respective one of the lower seat rails 85 a, 85 b. Each of the upper seat rails 84 a, 84 b extend rearwardly from a respective one of the opposite sides of the tube structure 77. Each one of a pair of posts 83 a, 83 b extends downwardly from proximate the front end of a respective one of the upper seat rails 84 a, 84 b. Each post 83 a, 83 b is pivotally coupled to a respective one of the front vertical member 91 a, 91 b of the chair frame 12 by a respective bolt extending through a respective pair of aligned apertures, one of the respective pair of aligned apertures being provided in a respective one of the posts 83 a, 83 b and the other of the respective pair of aligned apertures being provided in a respective one of the members 91 a, 91 b. This effects pivotal coupling of the seat 14 to the chair frame 12.

Each of the upper seat rails 84 a, 84 b is pivotally coupled to one end of a respective one of a pair of extendible/retractable support members 202 a, 202 b, at a point on the respective one of the upper seat rails 84 a, 84 b disposed rearwardly of the point of pivotal coupling of the upper seat rail 84 a, 84 b to the backrest 18. The pivotal coupling between each one of the respective pair of aligned apertures being provided in a respective one of the rails 84 a, 84 b and a respective one of the members 202 a, 202 b is effected by a respective bolt extending through a respective pair of aligned apertures, one of the respective pair of aligned apertures being provided in a respective one of the rails 84 a, 84 b and the other of the respective pair of aligned apertures being provided in a respective one of the members 202 a, 202 b. Each of the extendible/retractable support members 202 a, 202 b is also pivotally coupled at an opposite end to the backrest 16. The pivotal coupling between each of the members 202 a, 202 b and a respective one of a pair of opposing portions of the backrest 16 is effected by a respective bolt extending through a respective pair of aligned apertures, one of the respective pair of aligned apertures being provided in a respective one of the members 202 a, 202 b and the other being provided in a respective one of an opposing pair of portions of the backrest 16. The members 202 a, 202 b enable positioning and support of the backrest 16 in various positions of inclination relative to the seat 14, as is further described below.

Each of the lower seat rails 85 a, 85 b is coupled to and extends rearwardly from a respective one of the posts 83 a, 83 b. Each of the lower seat rails 85 a, 85 b is coupled to a respective one of the pair of posts 81 a, 81 b at about a midpoint of the rail. Each of the posts 81 a, 81 b, extends upwardly from a respective one of the rails 85 a, 85 b and is pivotally coupled to a respective one of the extendible/retractable members 200 a, 200 b (see above). Each lower seat rail 85 a, 85 b also includes a respective one of two pairs of armrest sockets 86 a, 86 b and 87 a, 87 b.

As discussed above, the seat 14 can be pivotally coupled to the chair frame 12. Pivotal coupling of the seat 14 to the chair frame 12 facilitates pivotal movement of the combination of the seat 14 and the backrest 16 (where the backrest 16 is coupled to the seat 14, as is the case in the preferred embodiment, and as will be discussed below) relative to the chair frame 12. In this respect, the seat 14 is capable of moving from one position of seat tilt relative to the frame 12 to another position of seat tilt (ie. changing the desired degree of seat tilt).

Positioning and support of the seat 14 in various positions of tilt is enabled by the extendible/retractable support members 200 a, 200 b. The support provided by the extendible/retractable support members 200 a, 200 b is adjustable, in that the support members 200 a, 200 b can be locked in a first position, and then released to permit extension or retraction of the support member so that the desired degree of seat tilt can be changed, and then locked again once the seat 14 is positioned at the desired degree of seat tilt. This facilitates changing of the desired degree of seat tilt, while effecting support of the seat 14, upon the seat 14 being positioned to the desired degree of seat tilt. To accommodate this change of positioning, and as explained above, each of the extendible/retractable members 200 a, 200 b is pivotally coupled at one end to the chair frame 12 (ie. braces 98 a, 98 b) and at a second opposite end to the seat 14 (ie. posts 81 a, 81 b on the seat frame 18). Extendible/retractable members 200 a, 200 b are actuated for movement by hand actuators 201 a, 201 b.

Each of the extendible/retractable support members 200 a, 200 b is in the form of a gas cylinder or “spring” provided on the chair frame 12 to exert an upward force on the seat 14 to thereby resist a downward weight of a chair occupant. A suitable gas spring is a BLOC-O-LIFT locking gas spring using a Bowden cable system, as manufactured by Stabilus GmbH. A detailed drawing of an example of the extendible/retractable support members 200 a, 200 b is provided in FIG. 17.

The gas spring is a closed system consisting of a pressure tube 102 and a hollow piston rod 104 extending from the pressure tube 102. The piston rod 104 terminates in a piston within pressure tube 102. A compressed gas is provided within tube 102. The pressure tube 102 is separated into first and second chambers by a valve (not shown). The valve is actuated by a release pin which extends from the valve and through the piston rod 104, and extends externally of the piston rod 104 for actuation by release plate 106. When the valve is open, in response to depression of the release pin, the piston rod can be extended in a controlled, dampened manner at the defined gas spring force to the maximum extension, so long as the gas spring force exceeds any external opposing forces. Of course, supplementary external forces (such as a manual force) can be applied to supplement the gas spring force and assist in the extension of the members 200 a, 200 b. This results in extension of the extendible/retractable support members 200 a, 200 b. If, while the valve is open, an external force is applied to the piston rod in opposition to the gas spring force, and overcoming the gas spring force, the piston rod 104 will recede into the pressure tube, resulting in the shortening of the length (ie. retraction) of the members 200 a, 200 b. An example of how such an external force may be applied to effect retraction of the members 200 a, 200 b is application of a manual force to cross-member 40 of the backrest frame 34 in a generally downwards direction. As soon as the actuator pin is released from the outside, the valve will close automatically because of the gas pressure exerted on it. The piston or piston rod is then locked, as gas exchange between the chambers is interrupted. The cylinders may thus be releasably locked in a desired position upon the seat 14 becoming titled to a desired position. The valve is manually controlled by tensioning of a cable (such as a Bowden™ cable) connected to the release plate 106 in response to actuation of the hand actuator 107 (in the case of members 200 a, 200 b, this would be actuators 201 a, 201 b respectively).

Alternatively, such extendible support members can be lockable helical springs or a ratchet mechanism.

The seat 14 is coupled to the chair frame 12 such that the vertical distance accommodates a suitable floor to knee height for bariatric patients using the chair. For example, the seating surface 20 of the seat 14 at the front edge 24 of the seat 14 is disposed above the reaction surface 8 (see FIG. 2) by a vertical distance of 21 inches. As a further example, the vertical distance is 23 inches.

Referring to FIGS. 1, 2, 13 and 14, the backrest 16 includes a backrest frame 30 and a backrest front surface 32. In the illustrated embodiment, the backrest frame 30 is coupled to the seat frame 18. It is understood that it is not necessary to couple the backrest frame 30 to the seat frame 18, and that coupling between the backrest frame 30 and the chair frame 12 may be effected directly with the chair frame 12 independently of the seat frame 18. However, where it is desired to facilitate pivotal movement between (i) the combination of the seat 14 and the backrest 16, and (ii) the chair frame 12 (ie. tilting of the seat 14) as it is in the preferred embodiment, the backrest frame 30 is coupled, and more particularly, pivotally coupled to the seat frame 18.

The backrest frame 30 is pivotally coupled to the seat frame 18 at each of the upper seat rails 84 a, 84 b, so as to facilitate pivotal movement (ie. movement into various positions of inclination) of the backrest 16 relative to the seat 14 and the chair frame 12. In order to facilitate pivotal movement of the seat 14 and backrest 16 (ie. movement into various positions of seat tilt) relative to the chair frame 12, the backrest frame 30 is pivotally coupled to the seat frame 18. Pivotal coupling of the backrest frame 30 to the seat frame 18 enables movement of the backrest from one position of inclination (or “recline”) relative to the seat 14 and the chair frame 12 to another position of inclination (ie. changing the desired degree of backrest inclination).

The backrest frame 30 is formed of two unitary spaced apart side structures 34 a, 34 b comprising a plurality of elongated bar or tube members. For example, the tube members are 304 stainless steel, one inch diameter, 16 gauge (0.065 inch wall thickness) tubes.

Each of the unitary side structures 34 a, 34 b includes a respective one of main tube members 36 a, 36 b. Each of the main tube members 36 a, 36 b is pivotally coupled proximate the bottom end thereof to a respective one of the upper seat rails 84 a, 84 b of the seat frame 14, at a position forwardly disposed of the rear end of a respective one of the upper seat rails 84 a, 84 b. The pivotal coupling between each one of the members 36 a, 36 b and a respective one of the rails 84 a, 84 b is effected by a respective bolt extending through a respective pair of aligned apertures, one of the respective pair of aligned apertures being provided in a respective one of the rails 84 a, 84 b and the other of the respective pair of aligned apertures being provided in a respective one of the members 36 a, 36 b. This effects pivotal coupling of the backrest 16 to the seat 14.

Each of the members 36 a, 36 b extends upwardly from the seat frame 14. Each of the main tube members 36 a, 36 b is contoured to facilitate the desired shaping of the backrest support surface 32, as is further described below. The main tube members 36 a, 36 b are joined together at or proximate their respective upper ends by a substantially horizontal top member 38 extending between the main tube members 36 a, 36 b. A substantially horizontal cross member 40 is also provided and extends between the main tube members 36 a, 36 b and below the top member 38. The cross member 40 is pivotally coupled to one end of each of the extendible/retractable members 202 a, 202 b (see FIG. 4). This effects pivotal coupling of the extendible/retractable support members 202 a, 202 b to the backrest 16. As well, hand levers associated with operation of the extendible/retractable members 202 a, 202 b, are also mounted to the cross member 40. The cross member 40 also can be used as a stroller-style push handle for a caregiver to propel the chair 10. The cross member 40 is supported by a pair of spaced apart cross brace members 42 a, 42 b extending from the top member 38, and is also supported by a pair of reinforcing tubes 44 a, 44 b, where each of the reinforcing tubes 44 a, 44 b is coupled to and extends upwardly from a respective one of the main tube members 36 a, 36 b.

Positioning of the backrest 16 in various positions of inclination relative to the seat 14 is enabled by the extendable/retractable support members 202 a, 202 b. The support provided by the extendible/retractable support members 202 a, 202 b is adjustable, in that the support members 202 a, 202 b can be locked in a first position, and then released to permit extension or retraction of the support members 202 a, 202 b so that the desired degree of backrest inclination can be changed, and then locked again once the backrest 16 is positioned at the desired degree of inclination. This facilitates changing of the desired degree of backrest inclination, while enabling support of the backrest 16 upon the backrest 16 being positioned to the desired degree of inclination.

In this respect, the extendible/retractable support members 202 a, 202 b are in the form of a pair of gas springs is provided on the chair frame to exert an upward force on the backrest to thereby resist a downward weight of a chair occupant. A suitable gas spring is a BLOC-O-LIFT locking gas spring using a Bowden cable system, as manufactured by Stabilus GmbH. A detailed drawing of an embodiment of the extendible/retractable support members 202 a, 202 b is provided in FIG. 17. The general operation of the extendible/retractable support members 202 a, 202 b is the same as that described above for extendible/retractable support members 200 a, 200 b, with the exception that actuation of the members 202 a, 202 b is effected by hand actuators 203 a, 203 b, respectively.

The backrest front surface 32 is configured for receiving and supporting at least a portion of the upper torso of the chair occupant. Like the seating surface 20, the front surface 32 of the backrest 16 can be a continuous or a discontinuous surface, so long as the front surface 32 performs the function of providing the necessary support to the chair occupant. In the illustrated embodiment, the backrest front surface 32 includes a plurality of spaced apart vinyl straps coupled to each of and extending between the tube members 36 a, 36 b. An exemplary vinyl strap is an extruded vinyl strap (1.5 inches wide, 0.13 inches thick, with a convex radius along its width) manufactured by Twitchell Corporation.

The backrest front surface 32 includes an upper backrest front surface 46 and a lower backrest front surface 48. The lower backrest front surface 48 is recessed relative to the upper backrest front surface 46 in order to accommodate the lower torso of a bariatric patient who is occupying the chair 10. The space 52 within the recess is configured so as to accommodate and receive soft tissue in the gluteal region (ie. a “gluteal shelf”) of the chair occupant where such soft tissue has become displaced rearwardly as a result of the chair occupant being seated in the chair. The desirability of accommodating a gluteal shelf is pronounced with bariatric patients, where the presence of a gluteal shelf is particularly significant when a bariatric patient is disposed in a seating position. Without providing any space in a chair for accommodating the gluteal shelf, seating of a bariatric patient in a chair can be relatively uncomfortable.

In this respect, the backrest 16 includes a backrest front support surface 32 including an upper backrest front surface 46 and a lower backrest front surface 48, the lower backrest front surface 48 being recessed from, and merging with the upper backrest front surface 46 at a merged front surface 50. An upper backrest front merging surface 4602 extends upwardly from the merged front surface 50, and a lower backrest front merging surface 4802 extends downwardly from the merged front surface 50. The point of merger between the lower backrest front surface 48 and the upper backrest front surface 46 is defined by a point of inflection at the merged front surface 50. The merged front surface 50 is substantially disposed in a horizontal plane 1801 (see FIGS. 18 and 19). “Substantially disposed in a horizontal plane” means that the merged front surface 50 may or may not be disposed entirely in the horizontal plane, and that if not so disposed, various portions of the merged front surface may vary from being disposed at and/or slightly above and/or slightly below the horizontal plane. If there is deviation from the horizontal plane, such deviation is minor and will not be sufficiently significant so as to noticeably reduce the comfort of the chair occupant.

A portion 4604 of the merging surface 4602 extending upwardly from a portion of the merged front surface 50 (see FIG. 20D) is tangent to a merging surface plane 1003. A portion 4804 of the merging surface 4802 extending downwardly from a portion of the merged front surface 50 is tangent to a merging surface plane 1005. Each of the merging portions 4604, 4804 is disposed in a vertical plane 1019 having a normal axis 1021 which is perpendicular to the normal axis 1023 of a plane tangent 1025 to the most forwardly disposed front surface 1027 of the backrest front surface 32 (see FIGS. 20B and 20C). The plane 1803 has a front face which defines angle θ₁ relative to and above the plane 1805 (see FIG. 20A). The angle θ₁ is at least than 10 degrees. For example, the angle θ₁ between 10 degrees and 60 degrees. As a further example, the angle θ₁ is 30 degrees.

Where either of the merging surface portion 4604 or the merging surface portion 4804 is a discontinuous portion, such portion 4604 or 4804 is defined by an imaginary planar or substantially planar surface extending upwardly or downwardly from the merged front surface 50 and to an adjacent physical backrest front surface 32 portion (such as a vinyl strap, in the case where the backrest front surface 32 includes spaced-apart vinyl straps, as described above).

The lower backrest front surface 48 extends upwardly relative to and substantially from the seating surface 20 of the seat 14, and merges with the upper backrest front surface 46 at the merged front surface 50. “Substantially from the seating surface 20” means that the surface 48 may or may not be joined to the surface 20. If the surface 48 is not joined to the surface 20, the space between the surface 48 and the surface 20 is relatively small and not sufficiently significant so as to noticeably reduce the comfort of the chair occupant. For example, the space is not so large as to permit the gluteal shelf of the chair occupant to become wedged between surfaces 48 and 20.

The backrest surface 32 includes a top edge 47 and side edges 46 a, 46 b (see FIG. 19). The side edges 46 a, 46 b are joined by the top edge 47. It is understood that any of the top edge 47 or the side edges 46 a, 46 b can be continuous or discontinuous. In this respect, any of these edges can include discontinuous portions so long as such edges define the perimeter of the backrest front surface 32.

A length of the backrest surface 32 is defined as any distance of the backrest surface 32 (including any discontinuous portions of the surface 46) between the merged front surface 50 and the top edge 47 and along any vertical plane 1008 having a normal axis 1009 that is perpendicular to the normal axis 1011 of a plane 1013 tangent to the most forwardly disposed front surface 1015 of the backrest front surface 32 (see FIGS. 21 and 22). A width of the backrest surface 32 is defined as any distance of the backrest surface 32 (including any discontinuous portions of the surface 46) between the side edges 46 a, 46 b of the backrest surface 32 and along any horizontal plane 1017 (see FIGS. 23 and 24).

In the illustrated embodiment, the upper backrest front surface 46, extending from the merged front surface 50, is substantially planar. “Substantially planar” means that the upper backrest support surface 46 may or may not be planar. If the surface is not planar, the deviation from planar is minor and not sufficiently significant to be noticeable to the chair occupant, and such deviation may be the result of imperfections introduced during the manufacturing process of the chair or its individual components.

The upper backrest front surface 46 includes an upper backrest front surface portion having a minimum width and a minimum length. In this respect, the width and/or the length may not be the same across the entire upper backrest front surface portion but, rather, may vary from a minimum to a maximum. In the illustrated embodiment, the upper backrest front surface portion is substantially planar and substantially rectangular. “Substantially rectangular” means that the upper backrest support surface 46 may or may not be rectangular. If the surface is not rectangular, the deviation from rectangular is minor and not sufficiently significant to be noticeable to the chair occupant, and such deviation may be the result of imperfections introduced during the manufacturing process of the chair or its individual components. For example, the upper backrest front surface portion is the upper backrest front surface 46, and has a minimum length of at least 2 inches and a minimum width of at least 24 inches. As a further example, the minimum width is between 24 inches and 38 inches, and the minimum length is between 2 inches and 36 inches. As a further, further example, the minimum width is 26 inches and the minimum length is 12 inches.

The recessed disposition of the lower backrest front surface 48 relative to the upper backrest front surface 46 defines a space 52 of substantially the same cross-sectional area across the merged front support surface 50. “Substantially the same cross-sectional area” means that the cross-sectional area may or may not vary by a small amount across the merged front support surface 50. If there are variances, such variances are minor and will not be sufficiently significant so as to noticeably reduce the comfort of the chair occupant.

A cross-sectional area 49 of the space 52 is defined, or is definable upon relative movement between the seat 14 and the backrest 16 (such as by tilting of the seat 14 and/or reclining of the backrest 16), in a vertical plane 1019 having a normal axis 1021 which is perpendicular to the normal axis 1023 of a plane tangent 1025 to the most forwardly disposed front surface 1027 of the backrest front surface 32 (see FIGS. 25 and 26). This cross-sectional area of the space 52 is substantially defined or substantially definable within the vertical plane 1019 between the lower backrest front surface 48, the seating surface 20 of the seat 14, and a plane 1020 tangent to a respective portion (ie. that portion disposed in the vertical plane 1019) of the upper backrest front merging surface 4602. Referring to FIG. 25, the plane 1020 has a front face which defines or is positionable (by tilting of the seat 14 and/or reclining of the backrest 16) to define an angle θ₃ relative to and above a horizontal plane 1807, and the seat 14 is positioned so as to provide a substantially horizontal seating surface. The angle θ₃ is between 80 degrees and 153 degrees. In the embodiment illustrated in FIGS. 25 and 26, the angle θ₃ is 97 degrees. Where the seating surface portion 2001 is a discontinuous portion, the seating surface portion 2001 is defined by an imaginary planar or substantially planar surface extending between adjacent physical seating surface portions, (such as vinyl straps, where the seating surface 20 includes spaced-apart vinyl straps, as described above). The term “substantially defined or substantially definable”, as used above with respect to the cross-sectional area of the space 52, means that the measurable space between these components is an approximation of the actual area of the space 52 available to receive the above-described gluteal shelf, and that the measurable space may or may not deviate slightly from the area of the actual space 52. If there is deviation, such deviation is minor and will not be sufficiently significant so as to reduce the comfort of the chair occupant. The cross-sectional area is at least 30 inches². For example, the cross-sectional area is between 30 inches² and 100 inches². As another example, the cross-sectional area is 40 inches². The space 49 is provided for receiving excess flesh of a bariatric patient who is seated in the chair.

As used herein, the term “a substantially horizontal seating surface” describes the nature of the seating surface provided by the seat 14 when the seat 14 is in a certain position. When a human is seated in the chair 10 when the seat 14 is in this position, the virtual plane which intersects the body of the seated human, from the knees to the hips, is horizontal or substantially horizontal.

One aspect of space 52 is the depth of the recess. The upper backrest front surface 46 includes an upper front surface portion 54, and the lower backrest front surface 48 includes a lower front surface portion 56. The upper front surface portion 54 of the upper backrest front surface 46 is disposed, or is positionable to be disposed (for example, by tilting of the seat 14 and/or reclining of the backrest 16), forwardly of the lower front surface portion 56 of the lower backrest support surface 48 by a horizontal distance 1039, wherein each of the upper front support surface portion 54 and the lower front surface portion 56 is disposed in a vertical plane 1019 having a normal axis 1021 which is perpendicular to the normal axis 1023 of a plane 1025 tangent to the most forwardly disposed front surface 1027 of the backrest front surface 32 (see FIGS. 27 and 28). A plane 1041 tangent to the portion 54 of the upper backrest front surface 46 has a front face which defines or is positionable (by tilting of the seat 14 and/or reclining of the backrest 16) to define an angle θ₄ relative to and above a horizontal plane 1043 (see FIG. 29). The angle θ₄ is at least 85 degrees. For example, the angle θ₄ is between 85 degrees and 120 degrees. The illustrated angle θ₄ is 95 degrees (see FIG. 29). The horizontal distance 1039 is at least 3 inches. For example, the horizontal distance 1039 is at least 4 inches. As a further example, the horizontal distance 1039 is between 3 inches and 8 inches. In yet even a further example, the horizontal distance is between 4 and 8 inches. As a further, further example, the horizontal distance is 3 inches. The depth of the recess is characterized by the horizontal distance 1039 and is provided for receiving excess flesh of a bariatric patient who is seated in the chair 10.

The depth of the recess can also be defined relative to a portion of the merged front surface 50. A portion 1002 of the merged front surface 50 is disposed forwardly, or is positionable to be disposed forwardly (for example, by tilting of the seat 14 and/or reclining of the backrest 16), of a lower backrest front surface portion 56 by a horizontal distance 1045, where each of the portion of the merged front surface 50 and the lower front surface portion 56 is disposed in a vertical plane 1019 having a normal axis 1021 which is perpendicular to the normal axis 1023 of a plane 1025 tangent to the most forwardly disposed front surface 1027 of the backrest front surface 32 (see FIGS. 30 and 31). A plane 1051 (in this case, plane 1051 is the same plane as plane 1025) is tangent to the portion of the merged front surface 50 disposed in the plane 1019. The plane 1051 has a front face which defines or is positionable (for example by tilting of the seat 14 and/or reclining of the backrest) to define an angle θ₅ relative to and above a horizontal plane 1043. The angle θ₅ is at least 80 degrees. For example, the angle θ₅ is between 80 degrees and 115 degrees. In the illustrated embodiment, θ₅ is 90 degrees (see FIG. 32). The horizontal distance 1045 is at least 3 inches. For example, the distance 1045 is at least 4 inches. As a further example, the distance 1045 is between 3 inches and 8 inches. In yet even a further example, the horizontal distance 1045 is between 4 inches and 8 inches. In a further, further example, the horizontal distance is 3 inches.

Another aspect of this space 52 is the height of the recess. The height of the recess is, generally, the distance between a portion 1002 of the merged front surface portion 50 and a portion 21 of the seating surface 20 immediately below the merged front support surface portion 50. This distance is more particularly defined as the distance 1059 between a portion 1002 of the merged front surface 50 and a portion 21 of the seating surface 20. Each of the merged front surface portion 501 and the seating surface portion 21 is disposed in a vertical plane 1019 having a normal axis 1021 which is perpendicular to the normal axis 1023 of a plane 1025 tangent to the most forwardly disposed front surface 1027 (which, in this case, is the same as merged surface portion 1002) of the backrest front surface 32 (see FIG. 34). The seating surface portion 21 is also disposed in a plane 1051 tangent to the merged front surface portion 1002. Referring to FIG. 33, the plane 1051 (which, in this case, is the same as plane 1025) has a front face which defines or is positionable (for example, by tilting of the seat and/or reclining of the backrest) to define an angle θ₂ relative to and above a horizontal plane 1075, and the seat 14 is positioned so as to provide a substantially horizontal seating surface. The angle θ₂ is between 70 degrees and 133 degrees. (see FIG. 33). In the embodiment illustrated, the angle θ₂ is 90 degrees (see FIG. 33). Where the seating surface 20 includes discontinuous portions (see above), it is understood that the seating surface portion 21 may, in fact, be a discontinuous portion. Where the seating surface portion 21 is a discontinuous portion, the seating surface portion 21 is defined by an imaginary planar or substantially planar surface extending between adjacent physical seating surface portions, (such as vinyl straps, where the seating surface 20 includes spaced-apart vinyl straps, as described above). For example, the distance 1059 is at least 8 inches. As a further example, the distance 1059 is at least 10 inches. As a further, further example, the distance 1059 is between 8 inches and 13 inches. In yet even a further example, the distance 1059 is between 8 inches and 18 inches. In yet even a further, further example, the distance 1059 is 13 inches. The merged support surface 50 and the seating surface portion 21 are either spaced apart relative to one another by the distance 1059, or are independently positionable (for example, by movement of the backrest 16 or the seat 14 relative to the other, such as by tilting of the seat 14 and/or reclining of the backrest 16) to become spaced apart relative to one another by the distance 1059. This aspect of the space 52 assists in providing room for receiving excess flesh of a bariatric patient who is seated in the chair 10.

The recess extends from the merged surface portion 50 for a continuous distance of at least 12 inches along the merged surface portion 50. For example, the continuous distance is 26 inches. As another example, the continuous distance is between 12 inches and 38 inches. In one embodiment, the depth of the recess is substantially the same along this continuous distance, and the height of the recess is substantially the same along this continuous distance.

With respect to the depth of the recess, “substantially the same” means that the depth may or may not be the same along the merged front support surface portion. If there are differences, such differences are minor and are not sufficiently significant so as to noticeably reduce the comfort of the chair occupant.

With respect to the height of the recess, “substantially the same” means that the height may or may not be the same along the merged surface portion. If there are differences in height, such differences are minor and are not sufficiently significant so as to noticeably reduce the comfort of the chair occupant.

With respect to the depth of the recess along the merged front surface 50, for example, the merged front surface 50 includes a merged front surface segment 2002. The upper backrest front merging surface 4602 of the upper backrest front surface extends upwardly from the merged front surface 50 and a lower backrest front merging surface 4802 of the lower backrest front surface 48 extends downwardly from the merged front surface 50, such that the upper backrest front surface 46 merges with the lower backrest front surface 48 at the merged front surface 50. Each portion of the upper backrest front merging surface 4602 is disposed with a respective portion of the lower backrest front merging surface 4802 in a respective vertical plane 5000, wherein the respective vertical plane 5000 has a respective vertical plane normal axis 5002 which is perpendicular to the normal axis 1023 of the plane 1025 tangent to the most forwardly disposed front surface 1027 of the backrest front surface 32. Each portion of the upper backrest front merging surface is tangent to a respective upper backrest front merging surface plane and the respective portion of the lower backrest front merging surface is tangent to a respective lower backrest front merging surface plane. The respective upper backrest front merging surface plane has a front face which defines an angle θ₆ relative to and above the respective lower backrest front merging surface portion plane, wherein the angle θ₆ is at least 10 degrees. For example, the angle θ₆ is between 10 degrees and 60 degrees. As a further example, θ₆ is 30 degrees. Each portion of the merged front surface segment 2002 is disposed with a respective portion of the lower backrest front surface 48 in a respective one of the vertical planes 5000. Each portion of the merged front surface segment is tangent to a respective merged front surface segment portion plane, wherein the merged front surface segment portion plane has a front face which defines or is positionable (by seat tilt and/or back recline) to define an angle θ₇ relative to and above a horizontal plane, wherein θ₇ is at least 80 degrees, such as 90 degrees. For example, θ₇ is between 80 degrees and 115 degrees. Each portion of the merged front surface segment 2002 is disposed forwardly, or is positionable to be disposed (for example by tilting of the seat 14 and/or reclining of the backrest 16) forwardly, of the respective portion of the lower backrest front surface 48 by a horizontal distance 6000 of at least 3 inches. For example, the horizontal distance 6000 is between 3 inches and 8 inches. As a further example, the horizontal distance 6000 is at least 4 inches, such as between 4 inches and 8 inches. As a further, further example, the horizontal distance 6000 is 3 inches. The segment 2002 has a width 6002 of at least 12 inches. For example, the width 6002 of the segment 2002 is 26 inches. As another example, the width 6002 of the segment 2002 is between 12 inches and 38 inches.

For example, with respect to the depth along the merged front surface segment 2002 having portions 2004, 2006 in respective vertical planes 5102, 5202 (vertical planes 5000 include planes 5102, 5202), and referring to FIGS. 35 to 39, each of portions 4604, 4606 of the upper backrest front merging surface 4602 is disposed with a respective portion 4804, 4806 of the lower backrest front merging surface 4802 in a respective one of the vertical planes 5102, 5202 (see FIGS. 35 and 36), wherein each of the respective vertical planes 5102, 5202 has a respective vertical plane normal axis 5104, 5204 which is perpendicular to the normal axis 1023 of the plane 1025 tangent to the most forwardly disposed front surface 1027 of the backrest front surface 32 (see FIG. 36). Each of the portions 4604, 4606 is tangent to a respective upper backrest front merging surface plane 4608, 4610 (in this case, planes 4608 and 4610 are the same), and each of the portions 4804, 4806 is tangent to a respective lower backrest front merging surface plane 4808, 4810 (in this case, planes 4808, 4810 are the same). Referring to FIG. 37, the respective upper backrest front merging surface portion plane 4608, 4610 has a front face which defines an angle θ₆ relative to and above the respective lower backrest front merging surface portion plane 4808, 4810, wherein the angle θ₆ is greater than 10 degrees. In FIG. 37, the angle θ₆ is 30 degrees. Each portion 2004, 2006 of the merged front surface segment 2002 is disposed with a respective portion 4812, 4814 of the lower backrest front surface in a respective one of the vertical planes 5102, 5202. Referring to FIG. 38, each portion 2004, 2006 (only portion 2006 is shown in FIG. 38) is tangent to a respective merged front surface segment plane 2018 a, 2018 b (only plane 2018 b is shown in FIG. 38). The respective merged front surface segment portion plane (ie. plane 2018 b) has a front face which defines or is positionable (for example, by seat tilt and/or back recline) to define an angle θ₇ relative to and above the horizontal plane 2020 which is greater than 80 degrees, such as 90 degrees (shown). Referring to FIG. 39, each portion 2004, 2006 is disposed or is positionable to be disposed (for example by tilting of the seat 14 and/or reclining of the backrest 16) forwardly, of the respective portion 4812, 4814 (only portion 4814 is shown in FIG. 39) of the lower backrest front surface 48 by a horizontal distance 6000 of at least 3 inches.

With respect to the height of the recess across the merged front surface segment 2002, each portion of the merged front surface segment 2002 is disposed, or is positionable to be disposed (for example, by tilting of the seat 14, or reclining of the backrest 16), above a respective portion of the seating surface 20 by a vertical distance of at least 8 inches, wherein each portion of the merged front surface segment 2002 and the respective seating surface portion is disposed in a respective one of the vertical planes 5000. For example, the vertical distance is between 8 inches and 18 inches. As a further example, the vertical distance is 10 inches. Each portion of the merged front segment 2002 is tangent to a respective merged front segment portion plane. The respective seating surface portion 20 is also disposed in the respective merged front surface segment plane. The respective merged front surface segment plane has a front face which defines or is positionable (by seat tilt and/or back recline) to define an angle θ₈ relative to and above a horizontal plane, where the angle θ₈ is between 70 degrees and 133 degrees, and the seat 14 is positioned so as to provide a substantially horizontal seating surface.

For example, with respect to the height of the recess across the merged front support surface segment 2002 having portions 2004, 2006 in the vertical planes 5102, 5104 (vertical planes 5000 include planes 5102, 5104), and referring to FIGS. 35 and 40, each portion 2004, 2006 (only portion 2006 is shown in FIG. 40) of the merged front surface segment 2002 is disposed, or is positionable to be disposed (for example, by tilting of the seat 14, or reclining of the backrest 16), above a respective portion 2202, 2204 (only portion 2204 is shown in FIG. 40) of the seating surface 20 by a vertical distance 6002 of at least 8 inches, wherein each portion 2004, 2006 of the merged front surface segment 2002 and the respective seating surface portion 2202, 2204 is disposed in a respective one of the vertical planes 5102, 5202 (see FIG. 35). Each portion 2004, 2006 is tangent to a respective merged front surface segment portion plane 2018 a, 2018 b. The respective seating surface portion 2202, 2204 is also disposed in the respective merged front surface segment plane 2018 a, 2018 b (only plane 2018 b is shown in FIG. 40, and this is tangent to portion 2006). Referring to FIG. 40, the respective merged front surface segment plane 2018 a, 2018 b has a front face which defines or is positionable (by seat tilt and/or back recline) to define the angle θ₈ relative to and above the horizontal plane 2020, wherein the angle θ₈ is between 70 degrees and 133 degrees, and the seat 14 is positioned so as to provide a substantially horizontal seating surface. In FIG. 40, angle θ₈ is 90 degrees.

With respect to the cross-sectional area of the space of the recess across the merged front surface segment 2002, in each of the vertical planes 5000, a respective two-dimensional space is disposed in the respective vertical plane and is defined, or is definable upon positioning of the seat 14 relative to the backrest 16 (for example, by tilting of the seat 14 and/or reclining of the backrest 16), between: (i) the lower backrest front surface 48, (ii) the seating surface 20, and (iii) the respective upper backrest front surface merging portion plane (which is tangent to the upper backrest front surface merging portion disposed in the respective vertical plane 5000). The respective upper backrest front surface merging portion plane has a front face which defines or is positionable (by seat tilt and/or back recline) to define an angle θ₉ relative to and above a horizontal plane, wherein the angle θ₉ is between 80 degrees and 153 degrees, and the seat 14 is positioned so as to provide a substantially horizontal seating surface. The space has an area of at least 30 inches². For example, the space is between 30 inches² and 100 inches². As a further example, the space is 40 inches².

For example, with respect to the cross-sectional area 4900 of the space of the recess across the merged front surface segment 2002 having the portions 2002, 2004 in the vertical planes 5102, 5104 (vertical planes 5000 include planes 5102, 5104), and referring to FIGS. 35 and 41, a respective two-dimensional space is disposed in the respective vertical plane and is defined, or is definable upon positioning of the seat 14 relative to the backrest 16 (for example, by tilting of the seat 14 and/or reclining of the backrest 16), between: (i) the lower backrest front surface 48, (ii) the seating surface 20, and (iii) a respective upper backrest front surface merging portion plane 4608, 4610 (only plane 4610 is illustrated in FIG. 41, see also FIG. 35). Referring to FIG. 41, the respective upper backrest front surface merging portion plane 4608, 4610 has a front face which defines or is positionable (by seat tilt and/or back recline) to define the angle θ₉ to and above the horizontal plane 2028, wherein the angle θ₉ is between 80 degrees and 153 degrees, and the seat 14 is positioned so as to provide a substantially horizontal seating surface. In FIG. 41, the illustrated angle θ₉ is 97 degrees.

Optionally, a headrest 3000 may be provided, and releasably coupled to the backrest frame 30. The headrest is single axis height adjustable with the option of either a formed acrylonitrile-butadiene-styrene (ABS) head support or a contoured closed cell polyurethane foam head support.

The legrest 300 is pivotally mounted to the seat frame 18 at the posts 82 a, 82 b (see above discussion). The legrest 300 includes a leg support member 302 and a foot support member 304. The leg support member 302 depends downwardly from the posts 82 a, 82 b and is configured to support the calves of the occupant of the chair 10. The foot support member 304 extends forwardly from the leg support member 302 and is configured to support the feet of the occupant of the chair 10. The legrest 300 is moveable by and supported in an elevated position by a pair of extendible/retractable members 306 a, 306 b, similar to the extendible/retractable members 204 a, 204 b, but can be rated with a lower exertion force. Each of the extendible/retractable members 306 a, 306 b is pivotally coupled at one end to the legrest 300. In particular, each of the members 306 a, 306 b is coupled to a respective one of the arms 308 a, 308 b extending rearwardly from the leg support member 302 of the legrest 300 by a respective bolt extending through a respective pair of aligned apertures, one of the respective pair of aligned apertures being provided in a respective one of the members 306 a, 306 b and the other of the respective pair of aligned apertures being provided in a respective one of the arms 308 a, 308 b. Each of the members 306 a, 306 b is also pivotally coupled at a second opposite end to the chair frame 14. In particular, the second end of each of the members 306 a, 306 b is pivotally coupled to a respective one of the pairs of forks 94 a, 95 a and 94 b, 95 b (see FIGS. 1, 2, and 4) by a respective bolt extending through a respective set of three aligned apertures, one of the respective pair of aligned apertures being provided in a respective one of the members 306 a, 306 b and the other two being provided in each of a respective one of the pairs of forks 94 a, 95 a, and 94 b, 95 b.

The members 306 a, 306 b enable positioning and support of legrest 300. Extension of the members 306 a, 306 b urges the legrest 300 to rotate in an upwardly and forwardly direction, causing elevation of the feet of an occupant of the chair 10, and also causing extension of the calves of an occupant of the chair.

A hand actuator 310 is mounted to the lower rail 93 a, and coupled to the extendible/retractable members 204 a, 204 b, to effect unlocking of the extendible/retractible members 204 a, 204 b, and thereby effect pivotal movement of the legrest between various elevated and non-elevated positions. Operation of hand actuator 310 to effect actuation of the members 204 a, 204 b is similar to the operation of actuators 201 a, 201 b.

The chair 10 is particularly useful for seating of bariatric patients. In this respect, any of the above-described embodiments of the chair 10 can be used for the seating of persons having a body weight of at least 300 pounds.

Although the disclosure describes and illustrates preferred embodiments of the invention, it is to be understood that the invention is not limited to these particular embodiments. Many variations and modifications may occur to those skilled in the art within the scope of the invention. For definition of the invention, reference is to be made to the appended claims. 

1. An adjustable armrest assembly for a chair, the armrest assembly comprising: a stationary linkage which is connectable to the chair; an armrest member for supporting an arm of an individual when seated in the chair; a coupling member effecting coupling of the armrest member to the stationary linkage, the coupling member permitting travel of the armrest member relative to the stationary linkage; and, a locking element configured for acting on the coupling member to effect locking of the armrest member in any one of at least three indexed positions relative to the stationary linkage.
 2. The adjustable armrest assembly as claimed in claim 1, wherein the permitted travel of the armrest member relative to the stationary linkage is along an arc-like path.
 3. The adjustable armrest assembly as claimed in claim 2, wherein the coupling member is a swivel linkage.
 4. The adjustable armrest assembly as claimed in claim 3, wherein the swivel linkage comprises a stationary linkage coupling portion and an armrest coupling portion, the stationary linkage coupling portion being offset from the armrest coupling portion, the stationary linkage coupling portion further being rotatably coupled to the stationary linkage, thereby permitting rotatable movement of the swivel linkage relative to the stationary linkage, and the armrest coupling portion being rotatably coupled to the armrest member, thereby permitting rotatable movement of the swivel linkage relative to the armrest member.
 5. The adjustable armrest assembly as claimed in claim 4, wherein the armrest member includes an armrest coupling linkage for effecting the rotatable coupling to the swivel linkage, and wherein the locking element includes a detent pin which is biased to interfere with the relative rotational movement between the swivel linkage and the armrest coupling linkage, such that locking in an indexed position is effected by the detent pin being positioned in both a swivel linkage hole provided in the swivel linkage and in a respective armrest coupling hole provided in the armrest coupling linkage, the detent pin becoming so positioned when the swivel linkage hole and the respective armrest coupling linkage hole are disposed in an overlapping relationship, the swivel linkage hole and the respective armrest coupling linkage hole becoming so disposed upon relative rotational movement between the swivel linkage and the armrest coupling linkage.
 6. The armrest assembly as claimed in claim 5, wherein the locking element is coupled to one of the swivel linkage and the armrest coupling linkage.
 7. The adjustable armrest as claimed in claim 1, further comprising a threaded handwheel configured for acting on the coupling member and effecting locking of the armrest member in positions other than the at least three indexed positions.
 8. An armrest assembly for a chair, the armrest assembly comprising: a stationary linkage configured for coupling to the chair; an armrest member including an upper surface configured for supporting at least a portion of a forearm of a person when seated in the chair, wherein the upper surface includes an uppermost surface portion; at least two swivel linkages effecting coupling of the armrest member to the stationary linkage, each of the at least two swivel linkages including a respective stationary linkage coupling portion rotatably coupled to the stationary linkage for rotation about a respective swivel linkage-stationary linkage axis, and also including a respective armrest member coupling portion rotatably coupled to the armrest member for rotation about a respective swivel linkage-armrest member axis; wherein each of the at least two swivel linkages is characterized by a respective offset distance, wherein the respective offset distance is the distance between the respective swivel linkage-stationary linkage axis and the respective swivel linkage-armrest member axis in a plane which is tangent to the uppermost surface portion; wherein the at least two swivel linkages includes a most forwardly disposed swivel linkage, such that the swivel linkage-stationary linkage axis of the most forwardly disposed linkage is forwardly disposed relative to the respective swivel linkage-stationary linkage axis of each of the other of the at least two swivel linkages and the swivel linkage-armrest member axis of the most forwardly disposed linkage is forwardly disposed relative to the respective swivel linkage-armrest member axis of each of the other of the at least two swivel linkages; wherein the at least two swivel linkages also includes a most rearwardly disposed swivel linkage, such that the swivel linkage-stationary linkage axis of the most rearwardly disposed swivel linkage is rearwardly disposed relative to the respective swivel linkage-stationary linkage axis of each of the other of the at least two swivel linkages and the swivel linkage-armrest member axis of the most rearwardly disposed swivel linkage is rearwardly disposed relative to the respective swivel linkage-armrest member axis of each of the other of the at least two swivel linkages; and wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.2 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.
 9. The armrest assembly as claimed in claim 8, wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.5 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.
 10. The armrest assembly as claimed in claim 8, wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 2 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.
 11. An armrest assembly for a chair, the armrest assembly comprising: a stationary linkage configured for coupling to the chair; an armrest member including an upper surface configured for supporting at least a portion of a forearm of a person seated in the chair, wherein the upper surface includes an uppermost armrest surface portion; at least two swivel linkages effecting coupling of the armrest member to the stationary linkage, each of the at least two swivel linkages including a respective stationary linkage coupling portion rotatably coupled to the stationary linkage for rotation about a respective swivel linkage-stationary linkage axis, and also including a respective armrest member coupling portion rotatably coupled to the armrest member for rotation about a respective swivel linkage-armrest member axis; wherein each of the at least two swivel linkages is characterized by a respective offset distance, wherein the respective offset distance is the distance between the respective swivel linkage-stationary linkage axis and the respective swivel linkage-armrest member axis in a plane which is tangent to the uppermost surface portion; wherein the at least two swivel linkages includes a most forwardly disposed swivel linkage and a most rearwardly disposed swivel linkage; and wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.2 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.
 12. The armrest assembly as claimed in claim 11, wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.5 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.
 13. The armrest assembly as claimed in claim 11, wherein the most forwardly disposed swivel linkage has a respective horizontal offset distance which is at least 2 times longer than the respective horizontal offset distance of the most rearwardly disposed swivel linkage.
 14. A chair comprising: a chair frame; and an armrest assembly including: a stationary linkage coupled to the chair frame; an armrest member including an upper surface configured for supporting at least a portion of a forearm of a person seated in the chair, wherein the upper surface includes an uppermost surface portion; at least two swivel linkages effecting coupling of the armrest member to the stationary linkage, each of the at least two swivel linkages including a respective stationary linkage coupling portion rotatably coupled to the stationary linkage for rotation about a respective swivel linkage-stationary linkage axis, and also including a respective armrest member coupling portion rotatably coupled to the armrest member for rotation about a respective swivel linkage-armrest member axis; wherein each of the at least two swivel linkages is characterized by a respective offset distance, wherein the respective offset distance is the distance between the respective swivel linkage-stationary linkage axis and the respective swivel linkage-armrest member axis in a plane which is tangent to the uppermost surface portion; wherein the at least two swivel linkages includes a most forwardly disposed swivel linkage, such that the swivel linkage-stationary linkage axis of the most forwardly disposed linkage is forwardly disposed relative to the respective swivel linkage-stationary linkage axis of each of the other of the at least two swivel linkages and the swivel linkage-armrest member axis of the most forwardly disposed linkage is forwardly disposed relative to the respective swivel linkage-armrest member axis of each of the other of the at least two swivel linkages; wherein the at least two swivel linkages also includes a most rearwardly disposed swivel linkage, such that the swivel linkage-stationary linkage axis of the most rearwardly disposed swivel linkage is rearwardly disposed relative to the respective swivel linkage-stationary linkage axis of each of the other of the at least two swivel linkages and the swivel linkage-armrest member axis of the most rearwardly disposed swivel linkage is rearwardly disposed relative to the respective swivel linkage-armrest member axis of each of the other of the at least two swivel linkages; and wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.2 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.
 15. The chair as claimed in claim 14, wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.5 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.
 16. The chair as claimed in claim 14, wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 2 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.
 17. A chair comprising: a chair frame; and an armrest assembly including: a stationary linkage coupled to the chair frame; an armrest member including an upper surface configured for supporting at least a portion of a forearm of a person seated in the chair, wherein the upper surface includes an uppermost surface portion; at least two swivel linkages effecting coupling of the armrest member to the stationary linkage, each of the at least two swivel linkages including a respective stationary linkage coupling portion rotatably coupled to the stationary linkage for rotation about a respective swivel linkage-stationary linkage axis, and also including a respective armrest member coupling portion rotatably coupled to the armrest member for rotation about a respective swivel linkage-armrest member axis; wherein each of the at least two swivel linkages is characterized by a respective offset distance, wherein the respective offset distance is the distance between the respective swivel linkage-stationary linkage axis and the respective swivel linkage-armrest member axis in a plane which is tangent to the uppermost surface portion; wherein the at least two swivel linkages includes a most forwardly disposed swivel linkage and a most rearwardly disposed swivel linkage; and wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.2 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.
 18. The chair as claimed in claim 17, wherein the most forwardly disposed swivel linkage has a respective offset distance which is at least 1.5 times longer than the respective offset distance of the most rearwardly disposed swivel linkage.
 19. The chair as claimed in claim 17, wherein the most forwardly disposed swivel linkage has a respective horizontal offset distance which is at least 2 times longer than the respective horizontal offset distance of the most rearwardly disposed swivel linkage. 